Ana (Andrea Tivadar) and her boyfriend Tom (Tom Ainsley) are Americans travelling around Europe, who take a coach to a rural part of France where they expect to do farm work for a landowner, Richard (Steven Brand). The coach is involved in an accident, and when the two wake up everyone is gone, so they walk the rest of the way to Richard’s mansion. But Tom doesn’t get on so well with the landlord, and there’s something weird about the books in the house and records on the shelves.

Everything is just a tiny bit skewwhiff in this intriguing but flawed thriller, starting with the fact that although it’s supposed to be set somewhere near Provence’s lavender fields and about two Yanks, director Renata Gabryjelska is Polish, Tivadar is British-Romanian, and the rest of the actors are mostly either Brits or Poles trying to sound French. Apart, that is, from the magnificent Joanna Kulig, star of Paweł Pawlikowski’s Cold War, who is largely wasted in a small role here. It was actually shot in Poland, which is why the architecture doesn’t look much like France at all. But it turns out everything makes sense in a way when the big twist kicks in, a real doozy that would be unfair to spoil.

Unfortunately, that makes it very tricky to explain why the film doesn’t quite work. Basically, let’s say that the science part, on which the twist depends, is very tenuous indeed. And the script, by Błażej Dzikowski, based on an idea by Gabryjelska, isn’t nimble enough to dance around these core implausibilities. At least the cast is toothsome and pleasant to watch, especially Tivadar.

• Safe Inside is released on 7 June on digital platforms.