When a murder investigation is launched into the death of a young woman, a mysterious list of names is discovered in her shoe, prompting an inquiry not only to find the killer, but also to understand the list of names. Who wrote the list, and who do these names refer to?

One of those named, is widowed antique dealer, Mark Easterbrook (Rufus Sewell), who despite having found love again, with new wife Hermia (Kaya Scodelario), is still haunted by the tragic death of his first wife, Delphine. "The Pale Horse" tells the story of Mark's investigation into how and why his name came to appear on the list; an investigation that leads him to the peculiar home of a trio of rumoured witches, The Pale Horse, in the beautiful village of Much Deeping. Word has it that the witches can do away with a rich relative, by supernatural means alone...

Despite Mark's scepticism of the paranormal, he cannot help but be consumed by the increasingly strange and extraordinary things that begin to happen around him. Is this too the work of the witches of The Pale Horse, and does this mean he is next on their list? Or can he find a rational explanation and identify the killer before they catch up with him?