Agatha Christie’s Towards Zero writer explains key changes from book

The couple in question - Neville and Audrey Strange - are played by Oliver Jackson Cohen (The Haunting of Hill House) and Ella Lily Hyland (Black Doves), with Mimi Keene (Sex Education) joining the series as Neville's new wife.

As to be expected when it comes to adaptations, not every detail stays true to the original material, with screenwriter Rachel Bennette explaining the key changes she made lifting from the book to the screen.

Speaking of the book itself, Bennette said: "Christie is doing some very unusual things in Towards Zero. Most interestingly, she de-centres the detective in the story.

"She chooses to use Superintendent Battle, rather than Poirot or Marple – and indeed, Battle spends a lot of the case wishing he was Poirot – and then she splits the deducing duties between Battle and the character of Angus MacWhirter who is a guest at the hotel, and a wonderfully original Christie creation.

"This is all designed to serve the plot, but it also led me to feel that what interests her most in this book is character and theme, and so I found myself leaning into the richness of Angus’ character as the investigator figure.

"But that brought its own challenges, because he is very tangential to our central characters, and it quickly became apparent that I really did need a policeman to crack this extremely convoluted case."

For Bennette, it was Inspector Leach who "evolved quite organically from that process", who soon became a mixture of "Battle, Angus MacWhirter and Battle’s nephew Jim Leach who is the local policeman in the book".

She explained further: "In his DNA, our Inspector Leach is pure Christie, and he could only have walked out of the pages of Towards Zero."

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Other changes to the series "were driven by the dramatic challenges of the three hour drama, and the need to dig deeper into the characters and themes to find the emotional truths of the bigger story, and build the plot," according to Bennette.

From this, the screenwriter had to "reconceive a couple of the characters", notably changing the characters of Neville and Audrey "and the nature of their relationship".

"Audrey especially is a very hidden character in the book, which was impossible to sustain over the three episodes," Bennette added. "But she remains as powerfully charismatic as she is in the book, albeit of a very different stripe."

The official synopsis for Toward Zero teases: "Add to this a long-suffering lady’s companion, a mysterious gentleman’s valet, an exiled cousin with a grudge, a venerable family lawyer, an inquisitive orphan and a French con man, and soon there will be murder.

"A troubled detective must rediscover his purpose to untangle a toxic web of jealousy, deceit and dysfunction. Can he solve the crime before another victim meets their death?

"An explosive love triangle, a formidable matriarch and a house party of enemies. All compelled… Towards Zero."

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

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