Fermat's Room

Four mathematicians are invited to a house by someone who conceals their identity. There are no real names at the invitation; everyone uses the name of a mathematician. Before dinner starts the doors lock and riddles begin arriving on their phones. Whenever a riddle's time runs out, the walls of the room advance inwards. The subject is not the riddles but which of the four is hiding the reason they were invited. The shrinking room makes the pressure physical, but the real tension comes from the slow emergence of what the four have in common in their past. The form is built on a single location and a limited budget. The wall movement is produced by industrial presses and the mechanism is shown openly in the film; the trick is not hidden. Most of the riddles are genuine classical logic problems and the film really does leave the viewer time to solve them. That is an honesty the genre usually lacks: the answers are not invented afterwards. Luis Piedrahita and Rodrigo Sopeña share the direction. Lluís Homar, Santi Millán and Alejo Sauras are in the cast. Who it is for: viewers who like single-room puzzles and logic games. Who it is not for: anyone after character depth; all four are largely functions.