Poirot has been receiving letters signed A.B.C., taunting him and predicting murders. According to the letters, the first killing is slated to occur in Andover on 31 March. Poirot gives this information to the police, but Inspector Crome, who has replaced the retired Inspector Japp, dismisses the letters' contents as an April Fools Day prank. Poirot seeks out Japp, but he suddenly dies in his presence. When Alice Asher is found murdered in Andover, and she is quickly followed by Betty Barnard in Bexhill, Crome takes the letters more seriously. However, he refuses all offers of help from Poirot and confiscates his papers, believing that Poirot knows the killer. Unbeknownst to Poirot and the police, a down-on-his-luck travelling stocking salesman named Alexander Bonaparte Cust encountered both victims prior to their deaths. A new letter arrives, stating that the next location and victim will begin with the letter C, but Crome still refuses Poirot's help. He believes that Poirot lied about his credentials and therefore cannot be trusted.
Poirot is given another letter from A.B.C. by a neighbour who received it in error. It states that the next murder will be in the town of Churston. He telephones the home of Sir Carmichael Clarke to warn him, only to learn he has already been murdered. Poirot confirms that A.B.C. is killing in locations where Poirot has previously been, when he discovers a newspaper clipping describing how he helped to deliver a baby on a train stopped in Andover. Another letter indicates that Doncaster is the next location; A.B.C. signs "Giddy-Up." Crome and Poirot travel there. Crome believes that the next murder will take place at the race track. In fact, the intended victim is a ventriloquist named Dexter Dooley. However, A.B.C. mistakenly kills the wrong man.
Alexander Bonaparte Cust awakens in the men's toilet in the train station at Embsay. He finds the body of another victim, Ernie Edwards, and that he is holding the murder weapon. Cust flees the crime scene, throwing the knife away, along with his hat and coat. Poirot finds a pack of stockings in the victim's case and, after visiting the sales company, identifies the murderer as Cust, who is soon arrested. After talking with Cust, who has a brain tumour and suffers from constant headaches, seizures and blackouts, Poirot doubts his guilt. Sir Carmichael's brother, Franklin, thanks Poirot for apprehending the murderer and has a brandy with him. Crome subsequently arrests Franklin because his fingerprint, taken from the brandy glass, matches that on the typewriter in Cust's room. Poirot realises that Franklin set Cust up with the stocking salesman job and that the first two murders were covers for the murder of Sir Carmichael. Franklin would inherit his brother's money, after Lady Hermione died of cancer. Franklin is hanged for the murders and, in a flashback to Belgium during the war, it is established that Poirot was actually a priest, whose congregation was murdered in his church as part of the Rape of Belgium.
Reception
The review aggregatorRotten Tomatoes gave the series an approval rating of 70% based on 30 reviews, The website's critical consensus reads, "The ABC Murders liberally adapts the famed Agatha Christie mystery while retaining its thrilling spirit, thanks in part to the sly performance of John Malkovich, who inhabits Hercule Poirot with enough wizened panache to win over those who were skeptical of his casting. "[10] On Metacritic, the film holds a weighted average score of 58 out of 100, based on 10 critics, indicating "mixed or average" reviews.[11]
The Guardian gave the first episode four stars and praised Malkovich's performance.[12]The Times gave it four stars and found it enjoyable, also praising Malkovich.[13] Reviewing the finale, Metro praised Poirot's new backstory and declared it "mystery television at its finest".[14]
