One of the classic science-fiction Bs of the Cold War era, Don Siegel's Invasion of the Body Snatchers (1956) is reissued to coincide with the Sci-Fi Days of Fear and Wonder season that is running until the end of the year at BFI Southbank in London. Adapted from the 1955 Jack Finney novel, The Body Snatchers, which had been serialised in three parts in Collier's Magazine the previous year, Daniel Mainwaring's screenplay plays on the paranoia that was gripping postwar America. But it also retains a teasing ambiguity, so that it isn't entirely possible to detect the direction of its political leaning. However, Park Circus have wisely removed the bookending scenes that were added to tilt the balance towards an anti-Communist reading and, as a consequence, this disconcerting allegory (which was made for just $420,000) reappears in all its monochrome glory just as a terrifying disease is exacerbating the sense of dread already caused by a new surge of conflicting ideologies that have made the modern world such au unstable and unsettling place.

Doctor Kevin McCarthy returns to the sleepy Californian town of Santa Mara after attending a conference. Nurse Jean Willes is concerned by the behaviour of some of their patients, as they claim that family members and neighbours have changed personality overnight. McCarthy is naturally sceptical. But he takes note when recently divorced old flame Dana Wynter insists that middle-aged cousin Virginia Christine is so worried by father Tom Fadden's atypical manner that she could swear he has been replaced. However, he is taken further aback by young Bobby Clark, who is so scared by the perceived change in mother Eileen Stevens that grandma Beatrice Maude doesn't know how to calm him.

Psychiatrist Larry Gates tells McCarthy that they are dealing with a case of mass hysteria. But McCarthy is convinced when mutual friend King Donovan invites him over to inspect the humanoid torso lying on his pool table. Commenting on the unfinished appearance of the face and the absence of fingerprints, McCarthy notices the similarity to his host's physique and Donovan is suitably shocked to drop a bottle and cut himself. But Donovan is even more horrified later than evening when he shows up at McCarthy's place with wife Carolyn Jones to announce that his doppelgänger has assumed his features, right down to the wound on his hand.

Suddenly fearful for Wynter, McCarthy rushes to her property and finds her replica hidden in a bin in the basement. He waskes her from a deep sleep and invites her to stay with him for her safety. Yet Gates continues to dismiss their irrational fears and he accuses them of being deluded when Donovan and Wynter's duplicates disappear without trace. Yet, while things appear to be getting back to normal, McCarthy wonders whether his patients are putting on an act to waylay his suspicions. He gets his proof during a barbecue when he discovers two giant seed pods in his greenhouse, which burst open to reveal human counterparts lying in a sticky residue. Recognising his resemblance to one of the pod people, McCarthy stabs at it with a pitchfork, as she searches for lighter fluid to destroy the capsules.

Retreating to the house, McCarthy, Wynter, Donovan and Jones try to fathom out what is happening. They speculate about the role of the pods and conclude that an alien life form has developed the power to create physical likeness, while also being able to remove the emotions that make humans individual. McCarthy calls the FBI for help. But the line is dead and he has no more luck reaching the authorities in the state capital. Realising that they are in danger if they fall asleep, McCarthy tries to keep the exhausted Wynter awake by feeding her with stimulants from his surgery and warning her of the dire consequences if their neighbours allow their precious humanity to drain away.

The next morning, however, it is clear that the population has entirely succumbed to the pod process and that McCarthy and Wynter are the only two human beings left alive. As they watch pods being loaded into trucks in the busy street, McCarthy deduces that the aliens are using Santa Mara as a base for a nationwide takeover. He refuses to answer the door when Gates and Donovan knock on the door and urge them to give up quietly and enjoy the benefits of life without emotional baggage. However, Wynter sobs with despair at the prospect of a world without love and informs McCarthy that she wants to bear his children and would rather die than become a sterile clone.

Knocking out Donovan and Gates with hypodermic sedatives, McCarthy and Wynter try to impersonate pop people, as they walk through the town in the hope of finding a means of escape. However, Wynter betrays them when she screams at the sight of a dog nearly being run over by a truck and they have to beat a hasty retreat. They are pursued into the countryside and take refuge in an abandoned mine. For what seems an eternity, footsteps pound on the planking above their heads. But, when silence falls, McCarthy slips away to take a look around. He hears singing, but discovers it is coming from the radio of a truck being loaded up with pods.

On returning, he finds Wynter slumped in a corner and pulls her to her feet to prevent her from dozing off. As they leave the cave, they fall into a puddle. But, as McCarthy helps Wynter up and pulls her close to kiss her, he recognises the glazed stare of the replicants and he pulls away from the embrace in utter horror. Almost as soon as the truth dawns on McCarthy, Wynter begins to call to her cohorts and he sprints away. In desperation, he tries to hitch a lift from one of the cars on the nearby highway. But no one stops and his pursuers give up the chase because he is now so alone that he has become harmless, because no one will believe his fantastic tale.

Jumping off the back of a pod-filled truck bound for destinations across the country, McCarthy feels the full force of his indolence. He turns to the camera and exhorts: `Look, you fools. You're in danger. Can't you see? They're after you. They're after all of us. Our wives, our children, everyone. They're here already. YOU'RE NEXT!'

Six decades later, these words still have the power to chill. There's a deliciously dark irony in the fact that they were delivered by somebody named McCarthy, as Senator Joseph McCarthy had been a key figure in the so-called `Communist witch-hunt' that had divided Hollywood and led to the imposition of a blacklist to prevent those with socialist sympathies from working. But it is possible to interpret this as both a warning against the hysteria that had been whipped up over the previous decade by the House UnAmerican Activities Committee and such publications as Red Scare and as an anti-Communinst diatribe denouncing the suppression of free speech and expression,

The premise would be revived by Philip Kaufman in 1978 and Abel Ferrara in 1993, but these adept updates would never quite capture the mood of the nervous nation with quite such acuity. What makes the action so disconcerting is the absence of violence, as the pitiful earthlings are too powerless to put up a fight against such a stealthy and assured adversary. What's more, the colonising invaders emerge from pods in a manner that resembles birth and this seeming alliance between the extra-terrestrials and Nature suggests that our planet has rejected us because we have allowed our reckless emotions to diminish its resources and jeopardise its future with nuclear weapons.

But the real ingenuity lay in making human lookalikes the menacing monsters from outer space. This not only precluded the need to waste money on expensive effects make-up and rubber suits, but it also made the grim admonition all the more effective, as there were no ludicrous creatures to dissipate the message with unintentional laughter. The fact that the actors were reasonably unfamiliar further enhances the docudramatic authenticity, as there are no familiar star tics to distract from the tightening tension that Siegel generates with his unshowy direction. He is ably served by production designer Ted Haworth, cinematographer Ellsworth Fredericks and composer Carmen Dragon. Indeed, this is a choice piece of studio film-making that remains as potent as ever, despite efforts - not dissimilar to those made against Robert Wiene's The Cabinet of Dr Caligari (1920) - to corrupt its original intention by appending an unwarrentedly optimistic coda.

The focus switches to science fact in Lukasz Palkowski's Bogowice, which chronicles the advent of heart transplantation in Poland in the mid-1980s. Scripted by Krzysztof Rak, this feels no different from dozens of other medical melodramas, dating from MGM's Dr Kildare series in the late 1930s. The surgical sequences are graphic and pass muster with those who know no better. But, despite its roots in truth, the storyline follows the familiar formula in showing how a pioneer ahead of his time takes on sceptical superiors and uncomprehending officials and realises his dream after much sacrifice, risk, disappointment and personal heartache. Thus, while this is competently made and sincerely acted, it struggles to fire the imagination, especially for those unfamiliar with the achievements of Dr Zbigniew Religa.

Following an opening segment revealing the efforts of Jan Moll (Wladyslaw Kowalski) to perform the first heart transplant in Poland on 4 July 1969, the action shifts to 1983, as cardiologist Zbigniew Religa (Tomasz Kot) strides along darkened corridors to practice removing hearts from cadavers in the basement of a Warsaw hospital. Professor Waclaw Sitkowski (Jan Englert) warns him about pushing his luck with the administrators, while wife Anna (Magdalena Czerwinska) wishes he was less of a workaholic. But Religa is more determined than ever to improve upon current procedures when one of his favourite patients, Ewa (Malgorzata Lata), dies in theatre and he hasn't the heart to tell the young girl's grieving mother (Kinga Preis) that he has failed her.

While attending a conference in the United States, Religa is encouraged by the ageing Moll and by young doctors, Marian Zembala (Piotr Glowacki) and Andrzej Bochenek (Szymon Piotr Warszawski), who are just about to embark upon internships abroad. He promises to look them up if he ever gets a say in choosing his own staff. However, the board take a dim view of the methods used on Ewa and Sitkowski reluctantly backs his decision to take over his own clinic in the industrial town of Zabre. Anna is less enthusiastic, however, and refuses to leave her students in the capital.

Religa wonders what he has done when he first sees the shell of the long-abandoned building and learns from administrator Stanislaw Pasyk (Zbigniew Zamachowski) that they have no patients, no equipment and no funding. But the local Party boss promises to pull a few strings and Zembala and Bochenek arrive at the clinic along with pretty nurses Jolka (Magdalena Kaczmarek), Kalina (Magdalena Wróbel) and Goska (Milena Suszynska) and they lick the premises into shape in just 15 days in a wonderfully hackneyed montage cut to The Knack's `My Sharona'.

Sitkowski comes to Zabre to perform the first operation and he chides Religa for giving him such a simple case. But, as his colleagues are celebrating the grand opening, Religa receives news that the Ministry of Health has refused to allocate funding. However, he hides the secret from his staff and stands up to the bureaucrats when they summon him to answer for functioning without a state licence. Moreover, he continues to seek donors so he can attempt a transplant and drives like a maniac across the country when he is informed that a match for one of his patients has been found. But the donor dies on the table while Religa is arguing with a petty apparatchik and he smashes the phone in frustration.

Increasingly feeling the pressure, the chain-smoking Religa goes to see Anna. But she knows he is dedicated to his work and he returns to Zabre to find bailiffs trying to remove the apparatus because the clinic is so deeply in debt. Despite having no time for the Party, Religa goes to see the minister and returns with funding on the day that Romuald Cichon (Rafal Zawierucha) joins the team and Religa is so confident in his new status that he bawls out the secret policemen following Cichon, whose father was involved in the Solidarity movement. He also befriends kidney transplant pioneer Jan Nielubowicz (Marian Opania), who reminds him that medicine is sometimes about going out on a limb and warns him that many will be opposed to his proposals simply because they are afraid.

In October 1985, Religa is told that a brain-dead Warsaw biker is a match for one of his patients and he convinces his parents (Olga Milaszewska and Marek Sawicki) that their son will go down in history for helping another person live. Zembala similarly allays the fears of the recipient's wife (Sonia Bohosiewicz), who worries that her husband will cease to love her if he has someone else's heart. She is also concerned that he will inherit bad traits from the alien muscle. However, when Religa explains to Andrzej (Marek Siudym) that he has been chosen for the surgery, it is clear that he is not a particularly pleasant man, anyway, as he hopes the donor wasn’t gay or Jewish.

In the event, he only survives for six days with his new heart and the television news coverage changes from adulation to admonition. However, Religa has proved he can perform the delicate procedure and he is keen to make another attempt. But this patient dies after 30 days and he takes his anger out on nurses Magda (Marta Scislowicz) and Krysia (Karolina Piechota) when they try to stop him from driving home while drunk. Backed by his loyal team, he readies a third transplant in April 1986 and Bochenek is sent to find a pig's heart to keep the patient alive while they await news of a donor. But the man slips away and Religa announces during an investigation by the district attorney that he is closing the transplant unit down.

Distressed by a communication from the Poznan Healthy Authority condemning him as a killer, Religa goes on a drinking binge and Zembala asks Anna to come and care for him. They go to their lakeside retreat, but he can't stop thinking about where he has been going wrong. When Moll falls ill, Religa visits him in hospital and he suggests that he shows a little more humility. Inspired by his words, Religa calls on Ewa's mother and apologises for letting her down and she shrugs that her daughter's death was simply part of God's plan.

Returning to Zabre, Religa scribbles on a blackboard in his office and convinces Zembala and Bochenek that he has solved the problems they have been having and a fourth transplant bid in May 1986 proves successful, with the patient going on to live for another seven years. A closing caption reveals that the Zabre unit has since performed over 1000 heart transplants, but that Religa died on 8 March 2009.

The closing shot of medics in scrubs looking exhausted after an operation sums up the tone of this well-intentioned biopic. Religa and his cohorts are presented as heroes who overcame the hurdles placed in front of them by science and the state to save the lives of their fellow citizens. It would be hard to see such a film being produced during the Communist era, as there is so much open criticism of the system. But this still smacks of Socialist Realism and, with Bartosz Chajdecki's score swelling emotively, Palkowski comes close on more than one occasion to overdoing the Iron Curtain nostalgia.

Nevertheless, the period trappings have a ring of authenticity, while Piotr Sobocinski, Jr.'s restless camera captures the energy of Tomasz Kot's bullish performance, while also providing plenty of unflinching surgical close-ups. This docudramatic ambience is reinforced by the copious amounts of medical jargon in the dialogue. But, for all its worthiness, this remains a rather pedestrian and parochial picture that will appeal more to exiled Poles and medical historians than the average arthouse audience.

Specialised terminology also abounds in The Guarantee, Ian Power's adaptation of Colin Murphy's stage recreation of the financial crisis that enveloped the Republic of Ireland in September 2008. Filling the screen with floating newspaper headlines, stock market ticker readouts and phrases from official documents, Power seeks to overwhelm the viewer in much the same way that the tsunami of economic ill-tidings threatened to engulf a government that seemed dazzled by the data and daunted by the consequences of any decision it might take. But, instead of providing an insight into the desperate discussions that took place through the night as a nation held its breath, Power succeeds only in confusing the issue, while also making the drama unnecessarily perplexing by casting several actors in dual roles.

In an effort to establish the background, Power and Murphy (who opens out the action of Guaranteed! Himself) bombard the viewer with archival footage that suggests the reckless profligacy of the Celtic Tiger era and the extent to which politicians keen to court popularity allowed the boom to proceed unhindered. Indeed, the clip of Taoiseach Bertie Ahern opining that those intent on deflating the bubble should commit suicide is one of the most telling moments of the entire picture. But, as important are the news bulletin warnings of University College, Dublin professor Morgan Kelly, whose forecast of a dire housing market crisis was ignored by financiers and politicians alike and, thus, Ireland was entirely unprepared when Lehman Brothers collapsed on 15 September 2008 and companies like AIG and Northern Rock were sucked into the vortex.

Ahern had resigned several months before the clouds began to gather and his successor as leader of the Fianna Fáil party and as Taoiseach was Brian Cowen (Gary Lydon), who is shown to be so out of touch with the real world that he cannot change a pod in a Nespresso machine. Finance minister Brian Lenihan, Jr. (David Murray) is presented as a deeper thinker, whose status within a political dynasty made him somehow better suited to hatching a solution in the wee small hours, while Cowen gazed out of the window at Government Buildings across a still Dublin night.

But this is as deep as the characterisation gets in a scenario that presumes far too much prior knowledge about both the personalities involved and the workings of the Irish political and financial systems. But even the well-informed will struggle to fathom the rationale behind asking three performers to play two characters each. Morgan C. Jones doubles up as Anglo-Irish Bank chairman Seán FitzPatrick and a government adviser called O'Sullivan, while Peter Coonan essays both wheeler-dealing AIB chief executive David Drumm and the sombrely moustachioed Central Banker and Orla Fitzgerald doubles up as the CEO of an unnamed hedge fund company and as a cabinet insider named Kate Walsh (who appears to be wholly fictitious).

Granted, this might have worked well during the run and tour of the Fishamble Theatre Company's original production (which one can well imagine being unbearably tense within the confines of an intimate setting). But, even though it's clear that this is a low-budget enterprise, it would have made more sense to hire a couple of extra faces to avoid needless confusion, especially when the core material is already so hard to follow, as Murphy makes few concessions to those unacquainted with the intricacies of the high finance and low skulduggery.

In essence, just days after Ireland became the first eurozone country to slide into recession, Lenihan and his team sought to prevent the collapse of the entire economy by concocting a two-year blanket guarantee of the €440bn in liabilities amassed by Allied Irish Banks, Bank of Ireland, Anglo Irish Bank, Irish Life and Permanent, Irish Nationwide Building Society and the Educational Building Society. As the closing captions reveal, it proved to be a ruinous strategy that saddled future generations with an intolerable burden of debt and led AIB to be branded the worst bank in the world, as details of its irregular practices began to emerge.

Clearly, Murphy has taken his cues from Peter Morgan's patented brand of political drama. But, while it has the same ring of truth as Stephen Frears's tele-take on The Deal (2003), this has none of the clarity, severity and suspense that characterised JC Chandor's Wall Street thriller, Margin Call (2011), which explained complex concepts with a wit, precision and potency that is sadly lacking here. The surfeit of close-ups of fervently earnest expressions (that irresistibly recall Joey Tribbiani's definition of `smell the fart' acting in Friends) quickly becomes irksome, but the low point is the symbolic inclusion of a small child holding a teddy bear on the front row of one of Cowen's press briefings.

Murray works hard as the late Brian Lenihan, while Fitzgerald does what she can with what is evidently a token woman role. But, even though the Brechtian duality is obviously designed to imply the cosy cahootic nature of the relationship between the politicians and the money men, Jones struggles to delineate between his shady dealer and honest broker, while Coonan irresistibly recalls comedian Peter Kaye using glasses and tashes to differentiate between his characters in Phoenix Nights. Thus, while this is a subject worthy of dramatisation (especially as there has yet to be an official public inquiry into the causes and conduct of the crisis), this has to be put down as a missed opportunity.

Finally, this week, comes a Steinbeckian fable for our recessional times that not only reveals the sobering social impact of the economic crisis on the average American, but also exposes the hollowness of evangelical Christianity in provincial communities where things are currently too tough for such niceties as neighbourly charity, acceptance, forgiving and forgetting. Filmed alone over 18 months by director Jesse Moss, The Overnighters is one of the hardest-hitting documentaries of the year. But, as in the best Westerns, there are no clear-cut heroes and villains here. Indeed, rarely has French humanist Jean Renoir's maxim about everybody having their own reasons resounded more truly, as the residents of the burgeoning city of Williston struggle to apply the tenets of their professed faith to their daily lives, while their saintly preacher proves to be all-too-human.

The fracking boom has been changing the North Dakotan landscape since 2008. Indeed, only Texas now produces more oil than the Peace Garden State and the western burg of Williston has been one of the major beneficiaries. However, while the citizens are happy to profit from the windfall, they are less than enamoured of the influx of migrant workers seeking the decent wages that they have not been able to command since their own states were stricken by the credit crunch. Consequently, many have been forced to congregate at the Concordia Lutheran Church, where Pastor Jay Reinke allows labourers and hopefuls alike to sleep on his pews or in tents and RVs in the car park and grounds.

Among those to stake out their patch are Alan Mezo, an ex-convict from Spokane, Washington, who is trying to move on from 16 years behind bars and conquer his addictive personality by assisting Reinke with the Overnighters programme; Keegan Edwards, a family man from Antigo, Wisconsin, who is anxious at being away from his girlfriend Sabrina and their infant son, Darron; Keith Batten, an electrician from Tifton, Georgia, whose wife threatens to leave him for another man unless he comes home; Paul Engel, a New Yorker who despises the `greed is good' mentality of many of the new carpetbaggers; and Keith Graves, a truck driver from Los Angeles, who is also a long way from the family he adores.

Reinke is aware that members of the city council consider the interlopers to be scroungers and trouble makers and has a powerful enemy in David Rupkalvis, the Managing Editor of the Williston Herald, who is quite prepared to rabblerouse on behalf of his readers. Even some of Reinke's flock have their misgivings, while his long-suffering wife, Andrea, wishes he would devote less time to strangers and more to his children, Clara (20), Mary (18), Eric (15) and Ann (13)..

Always ready with an apposite passage of Scripture to counteract the accusations and insults, Reinke runs the risk of seeming a little holier than thou. He certainly believes in the rectitude of his mission, but he is also aware of the rewards he will receive for doing the Lord's work and his casual remark about everyone hiding behind a façade comes back to haunt him when the mood in Williston turns more hostile in 2012, following the murder of a schoolteacher by two outlanders. Parishioner Shelly Shultz echoes the thoughts of many when she tells Moss that the Overnighters have rape and pillage in their hearts and she finds an unlikely ally when Reinke asks Engel to move out of his bedroom in the family home so that he can protect Graves, who has admitted to being a sex offender and has become the target of a virulent outing campaign by Rupkalvis and his dogged reporters..

Feeling betrayed, Engel supplies names to the Herald and Reinke is soon being pursued for quotes by journalist Hank Stephenson, who is determined to prove that Graves is a menace to the city. Disconcerted by the growing tension at the church, Edwards moves his family to the rural backwater of Wheelock, some 40 miles from Williston. However, he is badly injured in a truck crash and Reinke increasingly starts to feel like he is fighting a losing battle. He takes some solace from putting a lost soul named Todd back on the bus to Phoenix, Arizona. But he receives a blackmail threat soon afterwards and has to break the news to Andrea that he has had a homosexual relationship.

The speed with which Reinke's house of cards comes tumbling down is utterly dismaying. He feels compelled to move out, as the council closes down the Overnighters programme in 2013. Moreover, he was subsequently defrocked by the Missouri Synod and has since managed to find work selling welding equipment to fracking companies. Chillingly, the man he tried to help by offering him a cot in his basement, has had a $2 million bond placed on his head after he was accused of human trafficking.

But, while his sympathy certainly rests with Reinke, Moss avoids passing judgement and strives to remain in the background as a genuine human tragedy unfolds before him. He is more than aware of Reinke's hubristic tendencies and recognises why his congregation feels so strongly about his extending parish hospitality without listening to their concerns or seeking their consent. Yet it is difficult not to have pity for the majority of the Overnighters, who have trekked across the country in the hope of restoring a little of pride by being able to put food on the family table once again. Similarly, it is far from easy to condone the methods of the newspapermen, who are never called upon to justify their own agendas, while they consistently harass Reinke and his guests.

Yet, as with Invasion of the Body Snatchers, it is impossible to reach definitive conclusions from the footage amassed by the doughty Moss (who was threatened with rifles and broomsticks during his sojourn) and edited in conjunction with his producer-wife, Amanda McBaine, and editor Jeff Gilbert. Every religion has more than its share of hypocrites and church-going folks have been shown to have feet of clay on the big screen since DW Griffith started making social melodramas in the late 1900s. But there is something pernicious about the alliance between the Second and the Fourth Estates in what amounts to the persecution of Jay Reinke. He may have made mistakes, but his heart appears to have usually been in the right place and it is a shame to see his compassionate enterprise used against him with such pitiless fervour. However, it should not be forgotten that one player in this sorry saga gets off scot-free and that is the fracking industry, which continues to make billions of dollars while failing to provide adequate accommodation for its workforce.