Cube

The characters wake in a cubic room with a hatch in each wall. Some of the adjoining rooms are trapped. Nobody knows why they are there.

Vincenzo Natali built exactly one 14-foot cube and changed the coloured panels between takes, which is why the film can present a vast structure while only ever having one room.

The trap that opens the film, in the first three minutes, is one of the most efficient cold opens in the genre and tells you the rules immediately.

The mathematics of the prime-number solution does not entirely hold up, which the film covers by having its characters be wrong about things.

Its actual subject is institutional culpability: nobody built it, nobody runs it, everybody involved did one small part of the job. That speech, from the architect, is the best writing in it.