Bandera negra (1986)

Begoña, a waitress at an elegant club in Bilbao, manages to get shipowner Javier Uriarte to hire her father, Patxi Barrenechea, as captain of the merchant ship Urkia. Begoña meets Esteban, the leader of a gang of ship thieves operating in the estuary, who is also traveling on the Urkia. The voyage turns out to be very different from what they expected, as the ship is transporting weapons to an African country.