Murder in Mesopotamia

While accompanying his friend Hastings to a dig in Iraq, Hercule Poirot becomes involved in the murder of an archaeologist's wife. The victim, Mrs. Leidner, had been receiving threatening letters signed by her first husband, who was known to have been killed in a train wreck. Did he survive? Was it his younger brother who was avenging his memory? Did Miss Johnson get rid of her rival for her employer's affections? Did Richard Carey kill the woman he publically announces that he hates? Is the French priest really who he pretends to be? And how many deaths will occur before Poirot unmasks the murderer?