How different is Sarah Phelps's The Pale Horse from Agatha Christie's original novel?

If you want a spoiler-free answer...

...we can tell you that the TV show is pretty different from Agatha Christie's novel! But that it builds on the original story in really interesting and weird ways! Which is exactly what you'd expect from a Sarah Phelps adaptation.

• The Pale Horse review: A camp horror whodunnit with style to spare

What happens in the novel? (Spoiler free!)

In the novel, the plot swings into action when a Catholic priest named Father Gorman is summoned to the deathbed of a Mrs Davis. We don't know what exactly she tells him before she dies but we do know that she mentions "wickedness... such wickedness" that "must be stopped".

However, the priest doesn't get much of a chance to act on her information. As the book's blurb notes, "Father Gorman did his best, but on the way home he was killed; on his body was discovered a list of names, mysterious in that the people listed had nothing in common; yet, when Mark Easterbrook came to inquire into the circumstances of the people named, he began to discover a strange connection between them, and an ominous pattern..."

What follows is a story about a trio of witches (!!), a list of names of people who keep dying from (apparently) natural causes, and Easterbrook's obsessive mission to find out what's really going on. Is there something supernatural going on here? Or is the truth more prosaic?

Plenty of the original story does make it to our screens, of course. The TV drama gives us Mark Easterbrook (Rufus Sewell), and the dying woman, and her mysterious list of names; it gives us the witches, and their home at the Pale Horse in the village of Much Deeping. But much has also been changed, as we've set out below...

How has The Pale Horse been changed from the novel? (Some spoilers!)

We've taken a look back at the 1961 novel and here's what we can tell you...

Mark Easterbrook is NOT on the list in the book! According to Christie's original plot, Easterbrook first hears about the list when bumps into an old uni pal, Corrigan, who's also the police surgeon who examined the dead priest's body. Easterbrook knows several people by the surnames on the list, and he also knows they are dead; he then becomes fascinated by a potential connection to Much Deeping and the three witches who live in a former pub called The Pale Horse.

But in the TV show, Easterbrook (Rufus Sewell) is on the list – with a question mark next to his name. This adds a lot more jeopardy for this character the very beginning. Is he next? What's it all about?

Zachariah Osborne is also not on the list in the book. In the novel, Mr Osborne is actually a pharmacist who says he witnessed a man following Father Gorman before he was bludgeoned to death. But the character (played by Bertie Carvel) has been given a revamp for the TV show, transforming from witness to potential victim.

The list is written by Father Gorman, not Mrs Davis. In the novel, a dying woman named Mrs Davis gives her last confession to Father Gorman, who scribbles down the names she tells him and puts the scrap of paper in his shoe for safekeeping. He's then promptly killed, and the police discover the note. But there's no sign of the priest in the TV drama, which instead has Mrs Davis put the note in her own shoe before she dies in the street.

Hermia's only a 'girlfriend'. The original story has Mark Easterbrook sort-of dating a woman called Hermia who he doesn't really like very much. "So handsome, so mature, so intellectual, so well read!" he observes to himself. "And so – how could one put it? So – yes, so damnably dull!" Thankfully for them both, he doesn't take things any further; instead (extra spoiler alert) he meets a woman called Ginger who helps find out the truth about the list, and at the end they get engaged.

Screenwriter Sarah Phelps has bumped Hermia (Kata Scodelario) up to the status of 'wife', but Easterbrook still doesn't really like her very much. He's still in love with his first wife Delphine (Georgina Campbell) who died when they were still newlyweds.

And does Easterbrook have a "first wife" in the book? Yep! But he certainly doesn't mourn her; it was an unwise marriage, they were too young, and she was cheating on him with another man when she died in a car accident in Italy.

There's no affair with Thomasina Tuckerton: In the novel, Thomasina Tuckerton is just a red-headed girl Easterbrook sees in a coffee shop; he finds out her name because she gets into a physical fight with another girl whose man she's apparently stolen. He then comes across her obituary in the newspaper a couple of weeks later.

Later, after he finds out that "Tuckerton" is on the list, he does some digging and finds out that she was an heiress whose stepmother has inherited all the money after Thomasina's very convenient, untimely death.

And wouldn't you know it? Most of the dead people from the list have relatives who've benefitted from their untimely deaths! What a coincidence!

The venerable Mr Venables: A lot of the novel hinges on a character called Oscar Venables, a wealthy man living in Much Deeping who's been in a wheelchair for years after contracting polio. But a pharmacist called Zachary Osbourne (see above) insists he witnessed Mr Venables in London – walking just fine! – following Father Gorman just before his murder. Could he somehow be the brains behind the witches' murderous operation?

Oscar Venables is played in the TV drama by James Fleet, and it certainly seems as though there's something fishy going on with him. But as the character of Father Gorman has been cut out of the story entirely (with the list discovered directly in Mrs Davis's shoe), his role in the drama is likely to be quite different.

What's going on with the witches? At this point it's tricky to tell, but so far the TV is actually quite faithful to the original Pale Horse! Thyrza Grey, Sybil Stamfordis and Bella Webb live together as a trio in Much Deeping, and each claims their particular powers.

• Where was The Pale Horse filmed?

So how's the story going to develop...?

Big character changes!

Sarah Phelps has played around with The Pale Horse's characters, re-purposing them for her story. In case you're curious, here are the characters whose changes aren't covered above...

• The book features Easterbrook's friend Ariadne Oliver, a celebrated detective novelist based on Agatha Christie who appears in several of her novels.
• David Ardingly, played Henry Lloyd-Hughes in the drama, is also Easterbrook's friend in the original novel. But he's not related to Easterbrook's aunt, Clemency Ardingly.
• In fact, Clemency appears to be a stand-in for Mark's wealthy and childless godmother, Lady Hesketh-Dubois, whose name is on the list. In the novel, she's recently died (much to the benefit of her nephew).
• Inspector Lejeune, played by Sean Pertwee on screen, is a friendly sort of policeman in the novel and has no beef with Easterbrook.

The Pale Horse begins on BBC One at 9pm on Sunday 9th February 2020