Agatha Christie (Ruth Bradley), a young mystery novel writer sets out to help solve a real-life murder case when a wealthy woman is found bludgeoned to death. With the help of the murdered woman's lover (Pippa Haywood), she assumes a disguise and a trap is set for the suspects. But she soon discovers that real-life cases are harder to solve, and this killer is far more cunning and dangerous than her fictional creations.
