You'll want to sharpen those wits before tackling this tricksy Spanish thriller with more hair-raising turns than a mountain road at midnight. Four brilliant mathematicians � think Carol Vorderman to the power of ten � are summoned to a remote location by the Fermat of the title.

Fermat's Room (12)
***
Dirs: Luis Piedrahita, Rodrigo Sopena
With: Elena Ballesteros, Federico Luppi

You'll want to sharpen those wits before tackling this tricksy Spanish thriller with more hair-raising turns than a mountain road at midnight. Four brilliant mathematicians - think Carol Vorderman to the power of ten - are summoned to a remote location by the Fermat of the title.

Placed in increasing peril, they are given a series of puzzles and forced to rely on their intelligence and each other to survive.

Why are they there? What is the connection between them? Is it cheating to take a calculator into the cinema?

Though some of the conundrums are so contrived they would put 3-2-1 to shame, directors Luis Piedrahita and Rodrigo Sopena barely give the audience time to wonder about how ridiculous it all is. An entertaining maths-based thriller: now there's a puzzle.

Glasgow Film Theatre till July 2.