German film-maker Jan-Ole Gerster has created an intriguing noir mystery starring Sam Riley and Stacy Martin. It has very good performances and witty visual ideas, but the dramatic shape and emotional focus could have been tightened and sharpened. Yet this is a smart film which pays its audience the compliment of assuming they are intelligent enough to work things out on their own in a drama of sexual tension and dangerously polite encounters, something like Jacques Deray’s The Swimming Pool or Paul Schrader’s The Comfort of Strangers.

Riley plays Tom, a tennis coach at a middling hotel resort in Fuerteventura in the Canary Islands. He has been here for almost a decade, increasingly unhappy with his aimless, pointless life of no worries, no responsibilities, spending nights just boozing, doing drugs and having endless one-night stands with women. Tragically, he is nicknamed “Ace” because he once got to play briefly on the hotel court with Rafael Nadal and gossip has embellished that anecdote into a (fictional) glorious victory over the tennis legend in front of hundreds of onlookers. But Tom is now descending into alcoholism, always waking up hungover in his car, or on the beach, or by the pool with no memory of the night before.

He finds himself strangely interested in a British couple, Anne (Stacy Martin) and Dave (Jack Farthing), who are rather more stylish and sophisticated than the hotel’s usual package-crowd clientele, and persuade him to give private lessons to their charming young son Anton (Dylan Torrell). He agrees to show them round the island, and they take him out to dinner, where Anne explains she is a failed TV actor whose brief appearances explain why people think they know her. Then it’s back to their room for drinks – and things lead to something dramatic and unnerving.

This is a drama with a twist in its tale, but Gerster clearly doesn’t want to spring the surprise on you in any obvious way, or after conventionally ingenious narrative misdirections. The penny is allowed to drop very slowly and almost imperceptibly, yet once the audience have grasped the point, they may be waiting for someone or something to make it explicit – or in the absence of that, just make clear the emotional effect that the awful truth is having. I’m not sure we get that in what is a reasonably long movie but it’s refreshing for a film-maker to opt for subtlety, and there are good performances from Riley, Martin and Farthing.