Toby Jones, Andrea Riseborough, Billy Howle and Kim Cattrall star in this two-part BBC adaptation of Agatha Christie's crime story. In 1920s London, Leonard Vole (Howle) is arrested for the brutal murder of wealthy heiress Emily French (Cattrall). While all the evidence points to Vole, his partner Romaine (Riseborough) takes to the stand as a witness for the prosecution in a complex bid to maintain his freedom. Can she and lawyer John Mayhew (Jones) prove Leonard's innocence in the courtroom and ensure his acquittal?