‘Moonflower Murders’ Ending Explained: Who Killed Frank Parris?

Moonflower Murders on Masterpiece on PBS reunites mystery fans with Lesley Manville ‘s modern-day sleuth Susan Ryeland as well as the fictional ’50s detective Atticus Pünd ( Tim McMullan ), a character whose books Susan once edited and now combs through, looking for clues to real life murders. Like its predecessor, Magpie Murders , Moonflower Murders twists Susan’s investigation up with that of Pünd’s, revealing how Atticus Pünd’s creator, deceased author Alan Conway ( Conleth Hill ) snuck clues to real crimes in his best-sellers. What results is an enchanting mix of modern day mystery storytelling with a loving period drama pastiche. What also results is not one, but two, thrilling murder mysteries for the audience to solve.

**Spoilers for all of Moonflower Murders , now streaming on PBS**

Moonflower Murders starts with the murder of Frank Parris (Mark Gatiss) at a gorgeous hotel in the English countryside. The case appears pretty open/shut, and one of the hotel’s immigrant employees is arrested for the crime. However, years later, Cecily (Amy Griffiths), the daughter of the hotel’s owners goes missing, but only after insisting Frank Parris’s true killer is hidden in the pages of a best-selling novel loosely inspired by the hotel, written by Alan Conway.

Given this, Cecily’s parents, Lawrence (Adrian Rawlins) and Pauline (Pooky Quesnel), track Conway’s editor, Susan Ryeland, down and pay her to do her own digging. With the help of Atticus Pünd himself, Susan takes on the case. Meanwhile, Susan reads Conway’s book, which is also full of twists and turns (and two killers) for Pünd to decipher.

So who killed Parris? What happened to Cecily? And who were the killers in Pünd’s murder mystery? Here’s everything you need to know about the end of Moonflower Murders …

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Moonflower Murders Ending Explained: How Does the Masterpiece Mystery on PBS Series End?

First thing’s first. Let’s solve Susan’s murder mystery.

Susan figures out that none other than Cecily’s husband Aidan MacNeil (Will Tudor) killed Alan Parris and later killed her to cover up his secret. Aidan is nicknamed “Leo” in the book’s dedication, a reference not only to his astrological star sign, but also his nickname as a male escort. We learn that Frank Parris recognized Aidan as a sex worker and attempted to force him to have sex with him as blackmail on the eve of his fairy tale wedding to Cecily. Aidan killed Frank to keep his secret and framed poor Stefan (Alec Secareanu), who was having an affair with Cecily.

Cecily never believed Stefan was guilty, so she searched for clues of his innocence. When she realized it was Aidan, she wanted to expose the truth…so Aidan killed her, too.

In Pünd’s storyline, we learned last week that starlet Melissa James (Rosalie Craig) had not been killed by her husband, John Spencer (Rupert Evans), but her lover, Dr. Collins (Liam Garrigan). After a row that left Melissa briefly unconscious, she phoned her lover to help her. However, he takes the opportunity to murder her. The reason? His wife had recently come into a vast inheritance, which he could only access if his affair was completely hidden. Before that, Dr. Collins’s hope was that Melissa could be his ticket out of his sleepy town.

However, there’s a problem. If Dr. Collins is the killer, then why did John Spencer die by suicide? Pünd pieces together that Spencer was murdered by none other than his plucky assistant, Madeline Cain (Pippa Bennett-Warner). We learn that Madeline was a Melissa James superfan who killed John Spencer out of revenge.

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“I decided that she was a lonely person, who probably didn’t have much of a family unit or support system,” Bennett-Warner told Decider during an interview at Summer 2024 TCA. “And she finds, weirdly that support system, in the obsession with Melissa. So she really gets validation from that.”

Bennett-Warner added that the character was a “bit nutty” and “complex.”

“I think she is kind of constantly wearing a bit of a mask,” she said. “And she’s really good at her job. She’s deeply efficient. Like if you if you want a good secretary, you’re hiring Madeline Cain. I think she’s going to deliver on all the deliverables. She’s going to be a step ahead of you at all times. Yet there’s something kind of obsessive and dark about her as well.” You know, because she’s a stalker and liar and killer…

Moonflower Murders ends with one last cheeky twist, revealing to the audience that Alan Conway hid the truth about the vile Frank Parris’s true killer in plain sight. “Madeline Cain” is an anagram of “Aidan MacNeil.” Clues upon clues!

So what inklings do we have that there might be a third Susan Ryeland show on Masterpiece on PBS?

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Will There Be a Moonflower Murders Season 2? Will Masterpiece on PBS Make a Third Susan Rylance Mystery?

Moonflower Murders is the second Masterpiece Mystery series set in the world of Anthony Horowitz’s Atticus Pünd/Susan Ryeland murder mystery books. So are there plans to make a third series after Magpie Murders and Moonflower Murders ? After all, Horowitz has recently finished the third book, Marble Hall Murders , which is set for a 2025 publication date…

When Decider spoke to Masterpiece executive producer Susanne Simpson this summer, she stressed that planning for a Marble Hall Murders series was in “early stages.”

“I just started reading it,” Simpson said . “And of course we have to put financing together to be able to make it. So we’re just in the early stages for that one.”

Likewise, series creator Anthony Horowitz revealed that he has zero intention of continuing the series past a third book or series.

“I think if we do do a third — and again, it is at the moment, only an if — that would be a very nice trilogy and I’d be happy to stop,” Horowitz told Decider.

“There’s always a danger of doing one too many, of doing the one that everybody says, ‘It was not quite as good as the one before.’ And that’s a book I never want to write and it’s a TV show I never hope to produce.”

So if Marble Hall Murders winds up making it to PBS, don’t expect anything else from Susan Ryeland after that.

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