Will 'Marble Hall Murders' Be Adapted as 'Moonflower Murders' Follow-Up?

Moonflower Murders wrapped up the second mystery in the Susan Ryeland series on PBS, but that doesn't mean the editor-turned-mystery sleuth, played by Lesley Manville, has solved her last case. Much like Magpie Murders, which introduced Ryeland, her author Alan Conway (Conleth Hill), and his mystery novels that mirror real-life cases, Moonflower Murders once again had two different mystery stories to solve, and once Susan reached the end of the Moonflower Murders novel in the series, she could solve the Moonflower Murders case in real life as well.

At the halfway point of the new series, author Anthony Horowitz, who also adapted his own work for screen, sat down with us to discuss the chances of another season and perhaps a more pressing question: Why call it Moonflower Murders instead of Magpie Murders Season 2? Considering the crowded landscape of television, isn't that risking viewers not putting the two together?

However, Horowitz was adamant that calling the second series Magpie Murders Season 2 would have been ridiculous, and it seems like Masterpiece never even considered it. "It's two completely different books," he explained to Telly Visions. "This show has no magpies, apart from a brief appearance in Episode 1. But this is an entirely different story set in the Moonflower Hotel." Moreover, when it comes to a potential third season, it wouldn't be Magie Murders Season 3 or Moonflower Murders Season 2. Instead, it will be named for the next book in the series, Marble Hall Murders. 

Part of the reason the novels aren't titled so that producers could give the series an over-arching name (much like, say, The Sidney Chambers Mysteries, which were rechristened Grantchester) is due to the way each came about. Horowitz never set out to write a trilogy (or even a duology). "Magpie Murders was an extremely difficult book to write," he admitted, saying that trying to figure out the logistics of writing a period-piece mystery within a present-day mystery took several years, so when his wife [executive producer] Jill Green asked if he would consider writing a second one because it would be easier to sell a series adaptation than a one-off, "It was a bit of a horrific thought."

However, given a moment to think about it, Moonflower Murders "popped into my head... Then, while we were filming Moonflower, Jill said, 'Maybe you should think about a third season and start writing a book.' And suddenly, I had an idea, and it made me smile. So, a third book appeared out of nowhere." Of course, it continues the M-title trend. "We like the M and M, so we stick with it. It seems to be my favorite alliteration—and, therefore, probably my favorite chocolate," Horowitz joked. 

Horowitz confirmed that if Masterpiece adapts the third book for a third season, it will be called Marble Hall Murders. However, he cautions viewers not to assume it's a done deal. "It depends on the success of Moonflower. We're excited by how it's been received by the press; we hope the audience is enjoying it. We will see how the show does; if everybody's happy, we will make Marble Hall Murders." 

As for what Marble Hall Murders will be about, the novel, coming to shelves in 2025, is very different. “Of the three books, I think it’s my favorite,” Horowitz said. “Alan Conway doesn’t appear, nor do quite a few other characters whom we know and love. Instead, we have a new set of characters and an interesting scenario.”

Here’s Horowitz’s synopsis of what’s to come in the third story:

"The book within a book is written by a young writer, Elliot Krace, [who is] doing a continuity novel. Conway is dead, and a new author has been shipped in to take over. Krace is a very damaged character with a dark secret buried in his childhood. He's hiding that secret in his book even as he writes it, and Susan realizes he could be writing a suicide note. So, she's trying to help and stop him from getting into trouble." 

Horowitz may tell everyone to be cautious with their optimism, but he clearly already has been thinking about what he needs to do to bring Marble Hall Murders to screen. “I can’t wait to cast him,” he gushed. “Elliot is the most wonderful part to play. He is a sort of devil and, at the same time, so sweet, damaged, and sad. He’s a lot of things and his relationship with Susan Ryeland…I think Lesley will have a lot of fun with it. Let’s hope we get to make it.” 

Even if Masterpiece decides the price point for Marble Hall Murders is too high, viewers can read the novel when it is published and get closure. 

All episodes of Magpie and Moonflower Murders are streaming on the PBS app, PBS Passport, and the PBS Masterpiece Prime Video Channel. The book that will make up a potential Season 3, Marble Hall Murders, arrives on shelves in 2025; hopefully, it'll also be adapted for a final set of episodes.