Based on the actual 11-day disappearance of famed mystery writer Agatha Christie in 1926, the film fictionalizes her whereabouts during that time. When her husband announces that he is leaving her for another woman, Christie creates a mystery out of her own life by hiding in a Harrogate hotel and plotting revenge on her spouse while all of England searches for her. The reporter who finds Christie tries to foil her plan and finally falls in love with her.