'I wouldn't scream if I were you. Unless you want the whole world to learn about your husband and his mistress.' Agatha Christie, in London to visit her literary agent, is boarding a train, preoccupied with the devastating knowledge that her husband is having an affair. She feels a light touch on her back, causing her to lose her balance, then a sense of someone pulling her to safety from the rush of the incoming train. So begins a terrifying sequence of events, for her rescuer is no guardian angel, rather he is a blackmailer of the most insidious, manipulative kind. 'You, Mrs. Christie, are going to commit a murder. But, before then, you are going to disappear.' Writing about murder is a far cry from committing a crime, and Agatha must use every ounce of her cleverness and resourcefulness to thwart an adversary determined to exploit her expertise and knowledge about the act of murder to kill on his behalf.