Fermat's Room

Films set largely in one room are tough to pull off on celluloid, with those adapted from stage plays, in particular, such as Sleuth (the original) and Deathtrap often struggling to escape their confines in any real cinematic sense. Perhaps all that is needed is for the action to be written specifically for the screen, then, since Fermat's Room - the feature film debut of TV writer/directors Luis Piedrahita and Rodrigo Sopeña - is taut, thrilling and entertainingly three-dimensional despite the fact that almost all the action takes place within just four walls.

Certainly Piedrahita and Sopeña must like a challenge, since in addition to their restricted setting, their chosen protagonists - four mathematicians - are hardly the stuff from which box office gold is usually made. And yet, they make a virtue out of these obstructions, confounding expectations with a very agile plot. It seems this pairing - behind a hit Spanish show about magic, Nada x Aqui (Nothing Here) - really do know how to perform sleight of hand.

The mathematicians - from very different backgrounds - receive a mysterious puzzle in the post. If they can solve it, they are told, they will be invited to attend a dinner party with other like-minded geniuses for some further cerebral gamesmanship. After sweating it out for a week, those that make it are sent details of where to meet and given the psuedonym of a famous mathematician. So it is that the ageing and eternally optimistic "Hilbert" (Lluís Homar), young, gifted and slightly smug "Galois" (Alejo Sauras), ice queen "Oliva" (Elena Ballesteros) and troubled - and possibly alcoholic - engineer "Pascal" (Santi Millán) descend on a house in the middle of nowhere.

Just minutes after meeting host "Fermat" (Federico Luppi), he receives a phonecall and heads off to the hospital and, moments after that a PDA in the room rings with a conundrum... and a time limit. It isn't long before the maths wizards discover they are thinking for their lives - since every time they miss the puzzle deadline, the walls of the room close in further. It seems if they don't work out both the puzzles and how to escape, they will soon be out of the equation all together.

Once the walls start to move, there's barely a moment to catch your breath as sharp editing, clever camera angles and good use of sound, as furniture in the room begins to splinter, squeeze the tension of every moment. Even scenes outside the room feature puzzles and tricks of their own. Recalling the sort of cleverly plotted drawing room devices used by Agatha Christie mysteries, you race to unravel the whys and wherefores before the final reel. The addition of the extra puzzles which the mathematicians are trying to work out - tricky, but easy enough for the most part to give viewers a fighting chance of trying to solve them - is nothing short of genius, since they too grab the attention and offer a workout for the audience's little grey cells. One or two leaps of faith are required, but with the action moving this swiftly, you'll be more interested in holding on tight for the ride than in picking holes. There's no doubt about it Piedrahita and Sopeña box clever.