The young Ramon Salazar, son of a village owner, dreams of becoming a pearl fisherman. His father agrees to let him experience this job. Ramon enters a forbidden cave, den of a giant skate nicknamed the Manta Diablo. He finds an oyster containing a black pearl of unusual size. His father donates it to the Virgin rather than sell it to dishonest traffickers. Shortly after, the flotilla of the village led by Salazar perishes at sea. Ramon must face the Manta Diablo with another fisherman to bring prosperity to the village ..