While attending a commemorative ceremony in Belgium, Maigret is approached by a terror-stricken man, Xavier Marton, who is convinced that his wife wants him dead. Maintaining his sense of scruples, the inspector is drawn into a complex trio that includes Marton, a collector of toy trains, his wife, a Madame Bovary-esque character to the extreme, and her sister, the mysterious Jany. Is this a case of paranoia or of well-founded suspicion? When Marton dies, Maigret no longer considers returning directly to Paris.