Ep 1. Episode 1

The ABC Murders is a British television drama series based on the classic mystery novel by Agatha Christie. The show follows the story of Hercule Poirot, a Belgian detective who is called upon to solve a series of murders. In season 1 episode 1, Poirot receives a letter from an anonymous source who identifies himself only as "ABC". The letter is written in a seemingly innocent tone, but it contains disturbing implications – that the sender plans to commit multiple murders, with the victims' initials following the order of the alphabet.

Poirot takes the letter seriously and tries to track down the sender, but his efforts are initially fruitless. Meanwhile, the first victim, Alice Ascher, is killed in her tobacco shop in Andover. Poirot travels to Andover to investigate, and he meets a number of potential suspects, including Alice's estranged husband, her lover, her employee, and a mysterious stranger who was seen visiting the shop in the days leading up to the murder.

As Poirot delves deeper into the case, he begins to uncover more clues and suspects. He discovers that Alice's husband has a motive for killing her, as does her lover. He also learns that the mysterious stranger is actually a writer who is doing research for a book he is writing.

Back in London, Poirot receives a second letter from ABC, this one accompanied by a newspaper clipping reporting Alice Ascher's murder. The letter taunts Poirot, telling him that he will not be able to solve the case in time to prevent further murders.

Poirot is determined to catch the murderer, but his efforts are hindered by a lack of evidence. However, he does have one important lead – the fact that the letters from ABC were typed on a specific make and model of typewriter. Poirot visits a shop that sells the typewriter in question and is able to trace the sale to a man named Alexander Bonaparte Cust. Cust is a traveling salesman who has a history of mental illness and who has been seen in the vicinity of each of the murders.

Poirot and his assistant, Inspector Crome, track down Cust and bring him in for questioning. But Cust claims that he is innocent and that he knows nothing about the murders. Poirot is not convinced, but he does not have the evidence he needs to arrest Cust.

As the episode comes to a close, Poirot receives a third letter from ABC, telling him that the murderer will strike again in Doncaster. Poirot and Crome hurry to Doncaster, but they arrive too late – the murder has already taken place. The victim is Betty Barnard, a young woman who was found dead on the beach.

The ABC Murders season 1 episode 1 sets the stage for a thrilling and complex mystery. As Poirot races against the clock to stop the killer, he must grapple with a variety of suspects and clues, each leading him further down a twisting and dangerous path. The episode introduces viewers to the world of Hercule Poirot and sets up a story that is sure to keep audiences on the edge of their seats.