El aval.

Psychologist Martín Rivera is one day invited for a coffee by a stranger named José Sagasti, who informs him that his grandfather had made a pact with his boss, "The Devil", who he did not comply. Therefore Rivera, as his only male descendant, becomes the guarantee of said commitment. Martín and his closest ones start to be intensively harassed by Sagasti, until the pact can be finally fulfilled.