It took me a while to get what kind of movie Siberia is. On the surface, it’s about a diamond deal that you know is going to go bad. You’re waiting it out until someone finally holds a diamond up to a loupe, shakes their head ruefully at the buyer, and then springs under the table as guns light up the room. But there’s also a love story going on. The film’s biggest problem is that it barely settles on what it is before the credits roll.

Lucas (Keanu Reeves) is a diamond dealer, on the hunt for his partner, Pyotr (Boris Gulyarin), and a stash of stolen diamonds. Bad weather and a closed airport grounds Lucas long enough for him to embark on a stopover affair with café owner, Katya (Ana Ularu), with whom he has precious little chemistry. If I was meant to perceive marital problems between Lucas and his wife, Gabby (Molly Ringwald), they needed to be made more obvious because she’s only in it for two scenes – and in one of those she’s merely being swept around a room on a laptop screen. When actors are as underused as this, you’re left wondering why they were cast in the first place.

Although the weather does eventually improve and the hunt for Pyotr does continue, by this time it feels like the film has played its hand: it’s actually a love story.

Only…is it, though?

Siberia has received some pretty grim reviews and for the middle part of the film they felt justified. I was bored. I just didn’t feel invested in the relationship between Lucas and Katya. Far from fiery and passionate, it was limp and uninteresting – the part of a stopover where you queue through border control, check uneventfully into an airport hotel room, shower, watch TV, and eventually drift off to sleep. But then the ending happened, and suddenly I was staring intently at the screen. Turns out it’s not a terrible film after all. It meanders, sure, and it wastes time and loses track of itself, but the final half-hour is intense and impactful. The score by Danny Bensi and Saunder Jurriaans is as accomplished (and as mournful) as their work on Last Days in the Desert, and the performances are all solid.

I was still left somewhat bothered by the senselessness of Lucas’s adultery, although he does offer something of an explanation (albeit a semi-incomprehensible one). He tells Katya, “My wife and I are old friends, and sometimes with an old friend you learn to squint away certain things…things you’d maybe rather not see. The thing about squinting – you can never be certain what you might not be seeing.”

And, in the end, that’s what the film is really about. Lucas is squinting. He’s so focused on that tedious love affair that he’s squinting away the threat that lies before him. Perhaps I was squinting too. It makes for a memorable finale, but whether the end justifies the means is a matter of personal taste.

Siberia comes to select UK cinemas and Digital HD from 16 November.