John is a shy and good-natured man who lives in Ceuta and does everything by correspondence, from studying a career or learning judo to getting a girlfriend. She is from Madrid and the time has come for Juan to meet her so he takes a boat to the peninsula. In the boat he coincides with Maria, a beautiful young woman who goes to the capital to study chant and which he had previously met accidentally. During the trip, foreign smugglers try to use John to pass inadvertently stolen diamonds in Tangier.

A tale of two families, the Mendozas and Alzagas, faced for generations by the water of a river separating their adjoining properties. Old grudges reappear when the two heirs fall in love.