56, rue Pigalle.

Lucien Bonnet, Jean Vigneron's manservant, blackmails his boss, who is having an affair with Inès de Montalban, married to Ricardo. Vigneron pays the sum but Lucien is killed by an accomplice, Baruch. Everything seems to accuse Jean who, for fear of compromising Inès, prefers to keep mum. Fortunately, his innocence will be proved thanks to a surprise witness. The two lovers flee to Congo while the husband soon forgets them, finding comfort in debauchery.