The B movie has always been the amuse-bouche of cinema. It is the type of movie where upcoming stars earn their stripes, mainstream stars cement their personas and there is space, if not the budget, for the crew to experiment. But regardless of the subject matter, B movies are usually made with a lightness of touch that mean no one has to take it all too seriously. In the current film environment, where movies have budgets of either pennies or bajillions, and the encroachment of long-form television and the internet continue to shrink the traditional movie audience, the B movie seems in danger of fading away. But then along comes Unknown, with major talent and backing to own this middle-of-the-road space in the distributor’s calendar.

Directed by Spaniard Jaume Collet-Serra, Unknown’s action moves confidently from set-piece to set-piece in a snowy Berlin. Martin Harris (Liam Neeson) is a botanist who flies in with his wife Liz (January Jones) for a conference. On arriving at a hotel, he realises that a crucial briefcase has been left behind and jumps into a taxi to retrieve it. And from there the twists begin, as if the pitch meetings said, ‘It’s Frantic meets Dirty Pretty Things.’ The taxi driver turns out to a Bosnian named Gina (Diane Kruger), although the movie neatly avoids mentioning that no woman who looks like Diane Kruger has ever been forced to drive a taxi. She is smart, fast on her feet and sympathetic to Martin’s plight. In an odd way, the character of Gina is everything the movie isn’t.

It’s hard to know if the problem lies with the script (by Oliver Butcher and Stephen Cornwell, based on a novel by Didier Van Cauwelaert), or in the editing by Tim Alverson. Even though it was filmed on location, it feels like one of those old Hollywood movies where soundstages stood in for exotic locations. But unlike those old movies, where atmosphere and tone were everything, almost everything in Unknown is just a little bit off. For a start, it’s easy to guess that Liam Neeson isn’t really a botanist. Then there’s Martin’s behaviour in the hospital, pressing the wrong points with his doctor (Karl Markovics), and before his strange encounter with the nurse/plot device (Eva Lobau). This slight sense of wrongness continues for the rest of the picture, with almost every character behaving the way they do because the script requires it, not because of human feeling or real-world consequence. And don’t make the mistake of questioning anything, lest you feel the plot tumbling down around you. The cumulative effect of Unknown is of a group of amateurs, frantically stumbling through a show which must go on despite the disintegrating stage about them.

It’s hard to figure out how this happened. Collet-Serra is an experienced director used to juggling difficult staging onscreen and colossal ego off. Neeson’s recent resurgence as an action hero means he handles himself like an old pro, although he certainly does not tax himself. Aidan Quinn and Frank Langella provide expert support in two smaller but essential roles. Major German actors such as Sebastian Koch, Bruno Ganz, Stipe Erceg, and Markovics play the supporting parts with intelligence and class. Ganz and Langella even have a fantastic scene together that feels like it could have been the start of a whole new movie. However, if you don’t think about it too much, the movie does work. It’s well paced, and looks terrific – clean and crisp. The cinematography by Falvio Martinez Labiano isn’t flashy, but there is a real sense of being hunched up with worry against the cold. A sequence in an art gallery could have been in an old film noir. The opening stunt, involving an escape from a car sinking into a river, is both immensely shocking and completely believable – whatever CGI was used was done tastefully. In fact all of the action sequences are well done. So it’s difficult to understand why Unknown just doesn’t quite tie together.

The extras on the UK DVD are only three brief promos about the film, which reuse the same snippets of footage, and junket interviews with Neeson, Kruger, Jones, Collet-Serra, and producers Joel Silver and Leonard Goldberg.