Baghdad, 1928. Agatha Christie has traveled to the excavation of the ancient Mesopotamian city of Ur to investigate an unsolved mystery: two years ago, the explorer and writer Gertrude Bell died there from a drug overdose. At the time, authorities believed that Bell had taken her own life, but a letter recently unearthed reveals she was afraid someone intended to kill her. Upon arrival, Agatha encounters Miss Bell's former rival, the enigmatic archaeologist Mrs. Woolley, as she is on the cusp of making a potentially lucrative discovery. Temperamental but brilliant, Mrs. Woolley quickly charms the famous novelist, but Agatha cannot ignore the possibility that her new friend might be a murderer. As Agatha stealthily begins to gather information, she discovers that her mission is not without considerable risks. With the killer poised to strike again, Agatha must use all of her skills to outwit a devilishly cunning adversary determined to stay hidden in the desert sands.