The story gets under way at a weekend house party where a scientist is murdered and his secret papers stolen. Putting his "little grey cells" in action, Belgian detective Hercule Poirot methodically pieces together the clues, revealing the culprit to be -- you guessed it -- the Least Likely Suspect.
The story recounts the murder of an itinerant Jew (Jules Maurice)by the village Burgomaster (Harry Baur.) Years go by and Baur's crime does not weigh heavily on his conscience. But at a banquet one night, the subject of the killing comes up and he faints, and is haunted from that point onward by the vision of the man he killed and the sound of the sleigh bells that first accompanied the victim's arrival in the village. And, to complicate matters for Baur, the son of the victim arrives, and proceeds to fall in love with Baur's daughter.
Misanthrope Raymond Ferray's life of peace and quiet is disrupted by the arrival of his new neighbors the Rovels. Lady Rovel designs on marrying her daughter Meg to the much older Marquis de Boisgenêt. Her mother agrees not to force her, however, if she can find a suitable alternative. Raymond, who despite himself has taken a great interest in Miss Rovel, helps her to find one.