A man picked up for wandering in obvious distress among the cars and buses on the Grands Boulevards. Questioned in French, he remains mute . . . A madman? In Maigret's office, he is searched. His suit is new, his underwear is new, his shoes are new. All identifying labels have been removed. No identification papers. No wallet. Five crisp thousand-franc bills have been slipped into one of his pockets. A distressed man is found wandering the streets of Paris, with no memory of who he is or how he got there. The answers lead Maigret to a small harbour town, whose quiet citizens conceal a poisonous malice.