Towards Zero ending explained: Who was the murderer?

Her guests are star tennis player Nevile Strange, who is her nephew, his ex-wife Audrey and his current wife Kay. Other key characters include lawyer Mr Treves and his ward Sylvia, Lady Tressilian's companion Mary, Nevile's cousin Thomas Royde, the mysterious Louis Morel, Nevile's valet Mac and Inspector Leach, all of whom are harbouring secrets. It wouldn't be Agatha Christie without a mystery or two to solve, after all.

But the main event, the killings, don't take place in the first episode, as we've come to expect.

As Treves puts it in the opening scene, a good murder shouldn't take place at the start of the story, but towards the end – in this case towards the conclusion of the second episode and the beginning of the third, allowing ample build-up as we learn about the key movers and shakers.

So, how did Lady Tressilian and Treves meet their respective ends?

Read on for a full rundown of the Towards Zero ending.

Towards Zero ending explained

Inspector Leach reveals all in front of those staying at Gull's Point after a tennis match with Nevile.

It was Audrey who had planted the evidence against Nevile to force a divorce. A compact mirror was hidden in her ex-husband's car, which was enough to put the heat on Nevile, who admitted his infidelity.

And that, announced Leach, was the catalyst for the murders.

Nevile, who was furious Audrey had left him after they promised never to be apart, sought revenge for her insolence.

At first, he attempted to sow seeds of doubt among the rest of the group, turning on the waterworks in the aftermath of his aunt's death, and feigning innocence when accused, even pointing the finger at Audrey.

He murdered Lady Tressilian to inherit her estate as her rightful heir, before she was given the opportunity to change her will.

He made a splash at Easterhead, a nearby bar, to grant himself an alibi. This was a journey that could supposedly be made only by ferry or car, surely to far to swim.

As it turns out, Leach came across an old photo of Nevile competing in a swim and concluded that the time and distance were within his capabilities.

Read more:

• Why there’s no murder in Agatha Christie's Towards Zero episode 1
• Agatha Christie's Miss Marple is making a return – great-grandson confirms new drama

During the tennis match with Leach, Nevile's shoulder seemed injured, likely from his swim earlier. He put Audrey’s make-up and hair on his jacket to make it seem she was the murderer while hiding her compact.

He was forced to murder Mr Treves after the police had wrongly arrested Matthew Hutton for Lady Tressilian's murder, so he could point the blame back towards Audrey.

Audrey had kept the secret of what happened to Peter James for all these years to protect Nevile, but she reveals the truth to Inspector Leach, seemingly implicating Nevile in his death after all. Nevile was therefore responsible for the decline of Thomas's standing and that of his family, which ultimately estranged him from his beloved aunt.

The ending sees Audrey, now free, declaring she could go anywhere she wishes, while Nevile is to be hanged for the murders.

Inspector Leach and Sylvia developed a rapport throughout the course of the series and with her carers now deceased, Leach becomes her guardian.

While there were numerous threads to unravel, Leach eventually got the bottom of it all, with Nevile responsible for the murders after all following a string of red herrings.

A typical Agatha Christie mystery if ever there was one.

Agatha Christie's Towards Zero will air on BBC One and BBC iPlayer from Sunday 2nd March.

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