In the middle of the Spanish countryside, a speleologist and a photographer explore a grotto to estimate its scientific value. When they return to the surface, they discover that the speleologist’s companion has been assaulted and almost raped. While heading to the police station to lay a complaint, they accidentally kill a stranger whom they mistake for the assailant. Sensing that these events will provide the opportunity for him to leave his dull life behind, a young police officer accepts a bribe to cover up the murder.