In postwar Paris, Jenny Lamour performs as a singer in a music hall, with her husband, Maurice Martineau, playing the piano. When Maurice sees Jenny getting close to an older businessman, Georges Brignon, he decides to track her to Brignon’s residence, planning to commit murder. However, upon arrival, he discovers that Brignon has already been killed by another person. Inspector Antoine leads the investigation, which points to Martineau as a suspect, unraveling his intended alibi.