There have been several films featuring only two actors. The best-known is Sleuth, which starred Michael Caine alongside Laurence Olivier and Jude Law in the 1972 and 2007 versions. Always more compelling, however, was John Boorman's Hell in the Pacific (1968), in which American pilot Lee Marvin and Japanese naval captain Toshiro Mifune fought for supremacy of a small island during the Second World War. But this simmering study of macho patriotism has now been surpassed for intensity and oppressive sense of place by Alexei Popogrebsky's How I Ended This Summer, which earned Sergei Puskepalis and Grigori Dobrygin the Best Actor prize at the Berlin Film Festival for their doughty performances as the veteran technician and callow graduate manning a meteorological station on a remote island inside the Arctic Circle.

Having been raised in the Soviet Union, Puskepalis is fiercely proud of continuing the monitoring work that commenced when a base was built on Archym Island in 1935. But Dobrygin is very much of the perestroika generation and he would much rather listen to his mp3 player or shoot video game adversaries than check the apparatus dotted around the twin headlands looking out on a vast expanse of ice-pocked sea. Consequently, when Puskepalis heads to the south lagoon to catch some trout to take home to his wife, Dobrygin oversleeps and misses a series of key readings.

However, the lost data is the last thing on his mind when Puskepalis returns, as he has been informed over the radio by mission co-ordinator Igor Chernevich that his colleague's wife and son have been killed in a plane crash. Having been angrily reprimanded for insulting the memory of those who had perished maintaining the station, Dobrygin hides the radiogram Chernevich had dictated and sabotages the connection to prevent operators Ilya Sobolev and Artyom Tsukanov from discussing the tragedy during the regular report transmissions.

Dobrygin even withholds the information that a ship is coming to collect them in a couple of days and allows Puskepalis to set off on a second fishing expedition. But when Chernevich calls to say that the vessel is stuck in pack ice and that a helicopter will be arriving within 24 hours, Dobrygin is forced to set out across the inhospitable terrain to find his partner and only narrowly avoids a confrontation with a ravenous polar bear. However, he still has to be rescued by Puskepalis and, on returning to base, a combination of cowardice, confusion and resentment causes him to blurt out the bad news on the beach.

An exchange of gunfire follows and Dobrygin seeks sanctuary in a ramshackle cabin near the isotope beacon. But, in his panicked conviction that Puskepalis is hunting him down, he touches the radioactive equipment and contaminates the fish supply after sneaking back to the main hut.

The ambiguity of the closing sequences considerably heightens the suspense of this already unbearable drama. Scrambling up and down cliff faces, sleeping rough and risking lashing waves to hide from what he presumes is a furious Puskepalis, Dobrygin becomes increasingly irrational as the physical and psychological strain takes its toll. But he proves to be his own worst enemy and is penitently surprised when his ordeal concludes on a note of unexpected poignancy.

Whether engaging in banal conversations or enduring brooding silences, Puskepalis and Dobrygin ably convey the pressures placed upon an already antipathetic camaraderie by months of confinement and isolation. Dobrygin particularly impresses, as he betrays his immaturity by petulantly defying his superiors and nervously stuffing sweet wrappers into the frayed arm of a chair while fretting about what to do for the best. But Puskepalis also has his moments, as he composes an awkwardly affectionate radio message to his wife and sombrely recalls a predecessor who went stir crazy on discovering that his companion had been cheating him.

In addition to his controlled pacing, Popogrebsky also tellingly highlights details within Gennadi Popov's cramped interiors. But it's his use of Sigitas Motaras's raucous sound mix and Pavel Kostomarov's widescreen digital vistas and delicate time-lapse sequences that best captures the contrasts in the duo's personalities and the ominous ruggedness of the relentlessly daylit landscape. Doubtless a surfeit of undetected socio-political symbolism lurks in the bleak Chukotka scenery. But Popogrebsky eschews the mysticism that blights so many Slavic insights into human fragility and, consequently, this compels as both a harrowing rite of passage and a disconcertingly unconventional thriller. By contrast, Brek Taylor and Elizabeth Mitchell's adaptation of Jane Rogers's novel Island works better as a mood piece than a revenge drama or magic realist fairy-tale. Exploiting the lowering loveliness of Rain Li's photography, the debuting directors courageously slow the pace and allow the atmosphere of the isolated Hebridean settings to seep into each frame. But their story-telling is hamstrung by heavy-handed artifice and some disappointingly patchy performances.

Twentysomething Londoner Natalie Press travels to the Scottish coast intent on confronting the mother who abandoned her as a baby. Amidst flashbacks to her childhood (when she is played by Nikki Tangen and Lauren Fagg) and her unhappy sojourn with foster parents Will Paice and Charlotte Wontner, Press reaches the remote village where Janet McTeer resides and seizes upon the discovery in Bunty McIvor's post office that she has a room to let in her rundown cottage. However, Press's purpose is deflected by the news she has a half-brother and her growing friendship with Colin Morgan is reinforced by the realisation that the over-protective McTeer is dying and the guileless teenager will be left alone to fend for himself.

Harking back to the earnest, introspective dramas in which Channel Four specialised in the 1980s, this is a carefully made three-hander that ably sustains the suspense as Press considers her options. But the tempest-tossed nocturnal escape bid is cumbersomely staged and the secret-filled denouement resoundingly anti-climactic. Yet, this remains insidiously effective, as Taylor and Mitchell make baleful use of both the silences inside McTeer's dimly lit parlour and the rush of the wind and waves that accompany the myths and legends with which Morgan regales Press with an eagerness that is tinged on his part by an unknowingly incestuous infatuation.

The mood is markedly more flamboyant in Frank Ripploh's Taxi Zum Klo, which was hailed on its release in 1980 as a landmark in gay cinema. Unrepentantly graphic, disarmingly playful, occasionally chauvinistic and always shockingly reckless, this largely autobiographical debut now stands as an invaluable record of pre-AIDS attitudes to sex, drugs and domesticity. However, it also takes great delight in taunting the bigots who still equated homosexuality with perversion.

Having described himself in an opening voice-over as `a normal, tired, neurotic, polymorphous perverse teacher', bearded Berliner Frank Ripploh arrives at school having started his day by nakedly clambering over neighbour Orpha Termin's balcony (after locking himself out while stealing her newspaper) and flirting with garage attendant Peter Fahrni. He's popular with his class and uses his pre-breakfast escapade to introduce a lesson on luck and misfortune. But away from bowling nights with his colleagues, Ripploh devotes his time to cruising the clubs, bathhouses and public conveniences of the divided city in search of conqusts.

Dropping into a downtown cinema, he makes the acquaintance of moustachioed manager Bernd Broaderup and drives him back to his place in his sports car. But, just as they are in the middle of bathing and seducing each other, they are interrupted by distraught stranger Millie Büttner, who is seeking sanctuary from her abusive boyfriend. Instead of offering her a bed for the night, however, Ripploh has Broaderup book her into a hostel for battered woman and they resume their love-making as though nothing had happened.

The meekly monogamous Broaderup moves in and Ripploh briefly enjoys having him fuss over him and cook him nice meals. But he can't resist the thrill of the chase, even though Broaderup is hurt by the sight of him cavorting with leather-chapped pick-up Hans Gerd Mertens and the encounter necessitates a visit to doctor Jürgen Möller for a deeply intrusive rectal probe (and a gleefully frank discussion of men's urges with prostitute Ulla Topf).

Ripploh proves to be more than a little kinky himself when he hooks up with Fahrni for a sado-masochistic session that is amusing followed by a discussion of soft furnishings with fellow teacher Valeska Gerstenberg. But he winds up in hospital after contracting a disease and has to endure the humiliation of being rejected by shades-wearing Ric Schachtebek after he slips off the ward and has cabby Hans Kellner ferry him to his favourite cottaging sites. However, he soon bounces back and dumps Broaderup on a subway train after a row at an all-night drag queen ball and he boldly arrives at school in his belly dancer costume and encourages the kids to act out their fantasies (no matter how subversive or destructive they are) on the roll of a dice.

Lacing the saucy action with clips from grainy porn flicks, Ripploh succeeds in lampooning promiscuity as much as celebrating it. Moreover, he also uses an educational film on the perils of paedophilia to rile the homophobes who brand all non-straight activity as deviant. But he also muses on the transcience of physical attractiveness in wondering whether his libido and bank balance will enable him to pursue his cherished lifestyle into old age, while the constant bickering with Broaderup demonstrates that being a couple is pretty much the same whatever one's orientation.

Finally, it's back to the wilderness for Ilisa Barbash and Lucien Castaing-Taylor's Sweetgrass, which marks the passing of a tradition that started in the mid-19th century as it follows the last ever flock of sheep over 150 miles through the Absaroka-Beartooth Wilderness in the summer of 2003. In fact, the footage was recorded over three years and has been edited together to suggest a single drive. Castaing-Taylor insists that the resulting documentary has not been `directed', as he maintained a strictly observational brief. But this still feels akin to a Flahertyesque bid to produce an American variation on Merian C. Cooper and Ernest B. Schoedsack's celebrated silent account of the Bakhtiari trek across what was then Persia in Grass (1925).

The opening scenes at Lawrence and Elaine Allestad's ranch in Big Timber, Montana suggest this is going to follow the elegiacally tough approach that French documentarist Raymond Depardon adopted for his Profils Paysans trilogy. But the charming close-up of a chewing sheep staring placidly into the lens and the droll long shot of a bleating flock jostling to squeeze into a pen are quickly replaced by images of the uncompromising daily business of sheep rearing, as beasts are sheared with muscular efficiency in claustrophobic sheds and ewes are duped into adopting abandoned lambs by dressing them in the fleeces of stillborns.

But the hardest work of all involves the annual three-month expedition into the Beartooth Mountains to allow the 3000-strong flock to take advantage of public grazing land. The entire Allestad family participates in the first stages of the journey, as the sheep bustle down a classic Wild West main street and into the wilds, with dogs scurrying hither and thither to prevent the wilful creatures from straying. Indeed, there's something of a jamboree atmosphere as teepees are pitched and ancient stoves assembled for a night under the stars. But the real task begins when veteran John Ahern and the inexperienced Pat Connolly are left to cope with the flock alone under vast skies on terrain that's as forbidding as it's beautiful.

In addition to the physical toll that it takes on man, horse and dog alike, the sojourn also involves long hours of boredom that is only relieved by tersely genial repartee and cell calls home that become increasingly emotional as missed sleep and weight loss are compounded by knee injuries and the very real threat posed by the bears who prowl the camp at night in the hope of feeding their cubs. Gun shots usually send the predators lumbering into the woods, but the odd sheep is lost and the dogs are allowed to feast off the discarded carcasses.

But it's the unruly behaviour of the sheep themselves that causes Ahern and Connolly the most trouble. For the most part, they content themselves with coaxing calls to steer their charges down inclines, through valleys and on to pastures. But one particularly frustrating ovine revolt prompts a torrent of agricultural language that contrasts hilariously with the softly spoken encouragement the shepherds give their horses and dogs.

Eventually, the ordeal ends and the sheepherders allow themselves the odd snatch of song as they negotiate the last miles. But, as Ahern drives back to the ranch in his boss's truck, he is suddenly faced with the daunting prospect of how to earn a living now that vocation to which he has devoted his life is about to be consigned to history.

Despite the latter attempt to deconstruct the cowboy myth forged in Hollywood Westerns, the film-makers spend as much time here bestialising the humans as they do anthropomorphising the animals. Consequently, with more baaing and kumbadaying being heard in Ernst Carel's sound mix than comprehensible conversation, we learn little about Ahern and Connolly as people. But we do come to appreciate that they belong to a brotherhood that was key to the making of America and it's impossible not to feel a profound sadness at the knowledge that their expertise and commitment is being employed for the final time.

Yet this is anything but a sentimental snapshot. Enduring his own hardships in tracking the drive while wearing a shoulder camera harness, Castaing-Taylor not only captures the majesty of the scenery in his often painterly compositions, but also the frustrations, deprivations, intangibles and dangers of living under canvas for weeks on end at the mercy of the elements and the potentially ferocious wildlife. Moreover, he also succeeds in revealing a country at a crossroads, with no obvious notion of where best to head next.