Fernand Martin, a schoolteacher in Nogent-le-Roi, is in love with Jacqueline, a postal worker and the older sister of one of his pupils. He asks for her hand in marriage, but her father refuses. One morning, he receives an appointment to Tahiti.
When young Dalia is mistakenly admitted to a mental institution, she is declared sane - but by a truly mad person pretending to be a doctor. The real doctor thinks she is insane - how can she escape this madness?
