One of the canal carters stumbled on the corpse of Mary Lampson, strangled in a stable near the lock: the find plunged Maigret into the damp world of barges and towpath cafes. The woman's husband, a retired English colonel, was curt and unhelpful on board his yacht. But gradually Maigret extracted an account of the garish whisky-sodden life they had led along the inland waterways of France. It called for a chase on a bicycle and a confession from a dying man to draw together all the strands of a curious and pitiful story.