May 1, 1929. A decomposing headless body is found inside an abandoned wooden box in Madrid's Atocha train station. The victim is later identified as a Barcelona businessman that vanished six months before.

Adapted from the novel by Juan Marse, the film shows two distant worlds in the Spain of the 50's, the suburban and the bourgeois, which are related through two characters, Manolo Reyes, vulgar motorcycle thief who aspires to escape poverty and Teresa Serrat, university student of bourgeois extraction seduced by the revolutionary cause.

Colometa is an average housewife with two children to care for in the late 1930's, as the Spanish Civil War is starting and her husband goes off to fight. She had been an ordinary woman working in a shop when she met the lively carpenter who married her, and their life together was without major problems. But now she is forced to raise her children under straitened circumstances, and after her husband dies, her life undergoes another major change as she marries for the second time. Underneath Colometa's acquiescent, forebearing exterior must lie just a few discontents, a few unrealized dreams - but they never surface as she blithely moves from one episode in her life to another.

A patient is released from a mental hospital to help the police find a student who disappeared a few days ago.