The discovery of a strangled woman near a canal lock forces Inspector Maigret to navigate the insular and secretive world of English expatriates living on French waterways. Maigret focuses his investigation on the victim's husband, a retired colonel whose reticence hides a history of alcohol-fueled instability. The narrative follows the inspector as he moves between the damp, industrial atmosphere of the canal and the confined, tense environment of the husband's yacht. Through patient observation and persistent questioning, Maigret attempts to reconcile the victim's public persona with the private reality of her life.

Readers frequently highlight the atmospheric quality of the canal setting, which serves as a backdrop for the investigation. Discussion often centers on the contrast between the stoic, reserved nature of the English colonel and the chaotic, alcohol-dependent life he led with his wife. Critics often note the efficiency of Simenon's prose, which avoids unnecessary flourishes while maintaining a high level of tension. The book is frequently cited for its ability to turn a seemingly straightforward crime into a complex study of human frailty and social isolation. Many readers appreciate the way the narrative builds toward a resolution that feels earned through Maigret's quiet, persistent detective work.