Towards Zero ending explained: Who kills Lady Tressilian?

Towards Zero is a BBC One television series based on the 1944 novel of the same name by Agatha Christie. Rachel Bennette adapted the novel for the screen, with Sam Yates serving as the director. The series consists of three parts and aired on Tuesdays between March 2 and March 16, 2025.

Disclaimer: The following article contains the author’s opinion and spoilers from Towards Zero. Reader’s discretion is advised.

In Towards Zero, Lady Tressilian is killed by her nephew, Nevile Strange, a celebrity tennis player with a murky past. He kills her for two reasons. The first is to secure his inheritance of the Tressilian estate as the rightful heir before his aunt can change her will and cut him out for his divorce. The second reason is to falsely get his ex-wife, Audrey, convicted of murder.

The events of the series take place at the Tressilian estate on the south coast of England in the 1930s, when everyone gathers for the holidays. While the narrative of the show closely follows that of the book, in Christie's original version, Nevile was not portrayed as a blood relative of the family but rather a ward of the patriarch, Sir Matthew. He grew up under a false name after killing a person during his childhood.

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Why does Nevile try to frame Audrey in Towards Zero?

In Towards Zero, Nevile attempts to frame his ex-wife Audrey for the murder of his aunt as part of his revenge for being publicly humiliated by her. Throughout their marriage, Nevile has been a serial philanderer, with Audrey suffering in silence. However, Audrey decides to take action when the star athlete gets together with Kay Elliot.

Audrey steals Kay’s monogrammed compact and plants it in Nevile’s car. Introducing that as proof of adultery, she sues him for divorce and forces a public confession of his actions. While Nevile pretends to be sorry and insists they remain friends, he actually starts plotting his revenge.

Nevile marries Kay, despite not being in love with her. He plans their honeymoon at the Tressilian estate in Gull’s Point, knowing that both Lady Tressilian and Audrey will be there, so he can eliminate the former and pin the blame on the latter.

To further his determination to incriminate Audrey, Nevile is forced to commit another murder, that of the family lawyer, Mr Treves, after his valet, Matthew ‘Mac’ Hutton, is arrested for Lady Tressilian’s death.

The character of Mac is an original addition to the show. He is introduced as the illegitimate son of Sir Matthew Tressilian and a teenage scullery maid. Lady Tressilian becomes aware of the affair and seemingly resents her husband for it.

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How does Nevile get caught as the killer in Towards Zero?

Inspector Leach, a World War I veteran turned police officer, uncovers Nevile to be the murderer and calls him out in front of everyone after a tennis match against him at Gull’s Point. He presents Nevile's motives: revenge against Audrey for humiliating him and a desire for control over the Tressilian estate.

Nevile spends the day at a nearby bar the day he kills Lady Tressilian to grant himself an alibi, as the journey to and from the estate can seemingly only be made by car or ferry. However, Leach discovers an old photograph showing Nevile taking part in competitive swimming, thus providing an alternative mode of travel on the night of the murder. As a result of the swim, Nevile's shoulder appears injured during the tennis match against Leach.

According to Leach, Nevile murders Treves to implicate him after his first attempt fails, with the police arresting Matthew for Lady Tressilian's murder. In the book, Nevile's choice of victim is further explained, with Treves being aware of Nevile's past as Peter James, a ward of Lord Tressilian who killed another child with a bow and arrow and proceeded to live under an assumed identity.

In the show Towards Zero, Audrey shares the details of Nevile's past with Leach, aiding in his investigation against the star tennis player.

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