The low-key Spanish import Fermat's Room falls into that (very small) sub-genre that I've just now designated as "math horror." (Vincenzo Natali's Cube also belongs in this group, and maybe even a few other movies that I can't think of right now.) This is a strange but engaging Spanish thriller in which four well-established mathematicians convene after receiving a mysterious invitation, and then find themselves trapped inside a shrinking room. The only way out is to solve a bunch of math riddles, but the biggest question is this: Why the heck is someone trying to kill four mathematicians in the first place?

Handsomely shot and boasting fine work from its five main only actors, Fermat's Room is the sort of mystery / thriller that will appeal to folks who enjoy a good mind-bender as much as they dig a good foreign flick. It's certainly not as bizarre (or nearly as bloody) as Natali's Cube, but I'm betting the films would make for a pretty interesting double feature all the same. And while some of the in-movie puzzles are relatively obvious (hell, they even borrow one from Jim Henson's Labyrinth!), the movie as a whole proves to be sort of a puzzle in its own right. The third act revelations might not be all that shocking, but they work well enough in the low-key context of the piece.