When you watch The Pale Horse, look out for a particular painting hung in the antiques shop of our protagonist Mark Easterbrook (Rufus Sewell). See, there, in the gold frame behind the desk: stark against a dark background, a lamb lies with its feet bound in a sacrificial pose. Its eyes are open, and it seems still to be alive.
If you’ve watched any of Sarah Phelps’s previous four Agatha Christie adaptations, the painting may seem weirdly familiar – and that’s because, as the screenwriter reveals, she’s slipped it into every one of her Christie dramas to date.
Agnus Dei, or Lamb of God, is an oil painting by the 17th century Spanish Baroque artist Francisco de Zurbarán. It’s an allusion to Christ, described by John the Baptist as “the Lamb of God who takes away the sin of the World.”
The painting has been a constant presence in Phelps’s Agatha Christie “quintet”, which began with And Then There Were None and continued with The Witness for The Prosecution, Ordeal by Innocence, The ABC Murders, and finally 2020’s The Pale Horse.
“When I was doing And Then There Were None, I put lots of paintings on the walls, and they were chosen quite specifically,” Phelps explained. “But the one I kept going back to was the Francisco de Zurbarán, which is the Agnus Dei, which is the trussed lamb. He’s the most astonishing painter, I love him.
“But when you ever read about the Agnus Dei it’s supposed to be this depiction of Christ’s love for his church and his sacrifice. But the lamb hasn’t got a choice. It’s not making a sacrifice, it is being sacrificed. You don’t know whether it’s alive or dead, it’s impossible to tell.
“And I just kept thinking, that kind of crystallised with me something to do with Christie – which is about: you’ve done something, and that something has trussed you, and so now you are headed in the direction and you don’t actually have any free will. You could have done a long time ago, but now you’re in this story. You are trussed, basically you’re on the path to perdition, and you put yourself there.
“And I just liked it as a little kind of weird clue about her, just to have in every single film. And it sort of added to the internal rubric of how all the films, how all the adaptations talk to each other… I like the idea of underpinning it with a bit of Baroque, Spanish religious art where there is no choice actually, we are just trussed, and the thing that we did has tied us – and now we wait for our fate.”
You’ll have to go back to the previous dramas to spot where the Agnus Dei appears, but in The Pale Horse we can tell you that it’s in pride of place on Easterbrook’s wall.
Phelps’ determination to include the painting also influenced her choice of profession for Mark Easterbrook, who – in the original novel – is actually writing a book on “certain aspects of Mughal architecture.”
“I thought, it’s not that much of a leap to make him an antiques dealer,” Phelps said. “But also because I wanted to make sure I had the de Zurbarán Agnus Dei on the wall. It’s been in every single film.
“And also to have him unboxing a polar bear, which was in the first one I wrote, And Then There Were None.”
But don’t get too carried away with the significance of the polar bear, as Phelps added: “It was a clue in And Then There Were None, it’s not really a clue here, it’s just an affectionate nod to: we started over here, and now we’re here.
“And also it’s f**king weird. Come on, suddenly there’s a huge polar bear! And it tells you something about plunder and dominion, I think, and about being a master of the universe.”
The Pale Horse airs on BBC One at 9pm on Sundays