Gloria is adjusting the traditional chulapa dress for her granddaughter Isa. The teenager has grown, and the dress no longer fits her. Although Gloria stopped attending the San Isidro festivities years ago, as she makes the first stitch to alter her granddaughter’s dress, she realizes that she will never wear it again.

A group of film students find themselves trapped in their university (ECAM, Madrid) under suspicious circumstances. With no way to communicate with the outside world, they must find out who is behind it all in order to survive the night.