Watch Agatha Christie's The ABC Murders

Without any warning, the A.B.C. murderer strikes again in the bathroom of Embsay station. An arrest is finally made and the country celebrates and breathes a collective sigh of relief

Despite being warned off the case by Inspector Crome, Hercule continues to conduct his own investigation into the A.B.C. killer. He receives another letter promising a murder in Churston. After trying and failing to intercept another murder, national interest in the killings and Hercule's involvement explodes. There is a pattern to the murders, the killer is following the ABC Railway Guide and choosing his victims by letters of the alphabet. Finally, Crome pays attention. Hercule receives another letter drawing his attention to Doncaster and after informing Crome, they try to get there before the A.B.C. killer. Doncaster is where A.B.C. makes their first mistake...

England, 1933. Hercule Poirot, older, greyer and no longer revered by the public, has been receiving mysterious letters from a stranger who calls themselves A.B.C. and the author has an obsessive, ominous interest in Hercule. Hercule alerts the police at Scotland Yard but he's met with utter disdain as the new hotheaded officer, Inspector Crome, refuses to see him. Meanwhile, Cust, a shy and poorly businessman, rents a room at Marbury Boarding House, run by the cantankerous Rose Marbury and her unloved daughter, Lily. From here he intends to start his new business selling stockings. Hercule receives another letter from A.B.C. forewarning something sinister in Andover. After unsuccessfully trying to warn Inspector Crome, he travels there himself and makes a shocking discovery - the brutally murdered body of Alice Asher with an ABC Railway Guide beside her body. Despite the police's confidence that the culprit was her alcoholic husband, Hercule believes that there is a killer at large. The police continue to reject Hercule's theories but he receives another letter from A.B.C. threatening a second murder in Bexhill. Hercule travels there immediately but he is too late once again - Betty Barnard, a flirtatious caf