Fermat's Room

Fermat's Room (La Habitación de Fermat, 2007) is a Spanish thriller directed by Luis Piedrahita and Rodrigo Sopeña — watch it online on iFILM. Four mathematicians who have never met each other receive invitations from a stranger calling himself Fermat. They are given aliases — Galileo, Pascal, Oliva, Hilbert — and brought to an isolated room to solve a single great puzzle.

Their host disappears. The walls start closing in. Each time the group fails to answer a mathematical riddle within the time limit, the room shrinks a little more. Lluís Homar, Santi Millán, Alejo Sauras and Federico Luppi play the four, each hiding something, each suspecting the others. The puzzle is not just on paper — one of them is the trap.

Shot on a minimal budget with a single set, the film wrings more genuine tension out of arithmetic and a timer than most thrillers manage with car chases. Stream Fermat's Room (2007) on iFILM.