1928. Agatha Christie leaves England for Baghdad, where two years ago, explorer and writer Gertrude Bell died from a drugs overdose. The authorities believed that Bell had taken her own life, but a letter now unearthed reveals she was afraid someone wanted to kill her. Bell writes that if she were to die, the best place to look for her murderer would be Ur, an archaeological site in Mesopotamia. Looking into Bell's death, Agatha discovers the mission is not without risk. She must use all her skills to try to outwit a killer who hides among the desert sands....