Begoña, a waitress at an elegant club in Bilbao, gets the shipowner Javier Uriarte to place her father (Alfredo Landa) as captain of the merchant ship Urkia. Begoña meets Esteban, the head of a gang of thieves that operates in the estuary and who also travels on the Urkia. The trip turns out to be very different from what was expected, since the ship is transporting smuggled weapons destined for an African country.