Four mathematicians, who do not know each other, are invited by a mysterious host to spend a weekend trying to solve a great enigma. They are given the names of some of the most important mathematicians in history, and the only thing they know about their host is his pseudonym: Fermat. The meeting point is an abandoned house; and the place that has been arranged for them turns out to be a shrinking room that will crush them if they do not discover what connects them all and why someone might wish to murder them.

Shot in: Barcelona, Sant Cugat, Valldoreix, Vall de Sau - Collsacabra (Vilanova de Sau), Folgueroles, Badalona, Calldetenes.