James Cawood’s Stone Cold Murder, as directed by Sue Wilson, is that unusual theatrical phenomenon, a thriller that actually thrills. Until the interval, I thought it one of the best I had seen, rivalling Ira Levin’s Death Trap or Frederick Knott’s Wait Until Dark. My opinion was adjusted in Act II, where an aura of menace and sudden shocks are replaced by unlikely revelation of who is who and what is what. It is still great entertainment, though.

The setting is a remote, wind-lashed hotel in the Lake District (superbly created by designer Tony Eden) which is first glimpsed, with its uncurtained French window just begging for some nasty apparition to fill it — one soon does — after a blast of piano music in creepy ‘dan-de-dan-dan’ style.

Here we join a young couple — newly risen from an afternoon nap — as they look back on their first season of ownership. Settling in for a lovey-dovey night by themselves over iceless gin and tonics (ugh!), Olivia Chappell (Elinor Lawless) becomes increasingly nervous after answering a phone call on which the line goes dead. Edgy conversation with solid, unflappable hubby Robert (Elliott Chapman) suggests that something from her past — she drops vague hints about this — is threatening to impinge on the present.

The arrival of a climber looking for a bed for the night adds significantly to the atmosphere of discomfort. Ramsey (Paul Brendan) is oddly self-confident, offering unwanted compliments to Olivia that hint at . . . well, the presence of a loony. He claims to have been caught in the sudden storm. But the story seems unlikely. Climbing in such a spot, in the depths of winter? And then he is found out in a definite lie . . .

The past so feared by Olivia really does appear to have resurfaced when her old squeeze Sam Stone (Nick Waring) arrives to make a quartet at the hotel. But very soon it ceases to be a quartet — at least as far as living people are concerned.

Stone Cold Murder
The Mill at Sonning
Until July 26
Tickets: 0118 969 8000. millatsonning.com