How did a woman holding a pistol in her right hand shoot herself in the left temple? What was the link between a ghost sighting and the disappearance of top secret military plans? How did the bullet that killed Sir Gervase shatter a mirror in another part of the room? And who destroyed the 'eternal triangle' of love involving, Valentine Chantry? Hercule Poirot is faced with four mystifying cases, each a miniature classic of characterisation, incident and suspense.