Juan (Antonio Banderas) has been trying to escape the sexual demands of his sister for some time. He now works at a nuclear power plant as a very specialized kind of welder. A gypsy girl has taken up with him, but is temporarily displaced in his bed by his sister who has found him again, after a brief search. At the same time, the sister is being wooed by an English engineer (Bruce McGuire) at the same plant, and gradually she relinquishes the hold she has held over her bother.