'Marble Hall Murders' Greenlit to Complete Susan Ryland Trilogy

We are in a golden age of murder mysteries on TV. Cozy crime like Grantchester, Father Brown, and Death in Paradise are all hitting double-digit seasons. Meanwhile, more highbrow fare aims to do something different with the genre, from Agatha Christie reimaginings like Murder Is Easy to upcoming comedy mysteries like Ludwig and Death Valley. But there's nothing on TV quite like Anthony Horowitz's Susan Ryeland stories, adapted from his own novels Magpie Murders and Moonflower Murders, which take a meta-view of the genre by enclosing a period piece mystery inside a contemporary one. Now, the third and final story, Marble Hall Murders, has been greenlit to complete the trilogy.

In an interview with Horowitz last fall during Moonflower Murders' run in the fall of 2024, the author confirmed Marble Hall would be the third and last installment of the novels, partly because he never meant for it to be two books, let alone three. "Magpie Murders was an extremely difficult book to write," he told Telly Visions in October 2024. The logistics of writing a period-piece mystery within a present-day mystery took several years, so despite his wife and executive producer Jill Green's suggestion that making it a series would be easier to sell as a TV adaptation, his first reaction was: "It was a bit of a horrific thought."

Horowitz eventually dreamed up Moonflower Murders, but he had no plans for a third book until filming for the second series commenced, and he realized how much he enjoyed working in this meta-fiction world he'd created. However, though Marble Hall will bring back Lesley Manville as Susan Ryeland and Tim McMullin as Atticus Pund, those are the only cast members Horowitz's novel plans to keep, making it less-than-ideal for TV audiences, but very much in keeping with Horowitz's idea of digging into the process of writing and reading mysteries.