The Thursday Murder Club Ending Explained Who The Killer Really Is

Quick rundown: The Thursday Murder Club is now on Netflix, and yes — the ending is fiddly. It keeps the cozy charm of Richard Osman’s book but changes a bunch of motives and tidy bits of plot. If you finished it and want the who-did-what broken down without spoilers held back, here’s everything you need, in plain English.

Who was killed — and who did it?

The film opens with the Thursday Murder Club — four retired sleuths played by Helen Mirren, Pierce Brosnan, Ben Kingsley and Celia Imrie — poking around in a local mystery when a property developer named Tony Curran turns up dead on the village green. That death kicks off a chain of investigations and red herrings.

Tony Curran

At first there are multiple suspects: Ian Ventham (David Tennant), who was Tony's business partner; Jason Ritchie (Ron’s son) who shows up in a photo at the scene; and Bogdan (Henry Lloyd-Hughes), a former employee. During a protest against Ian’s development plans, Ian collapses and dies on the spot — cause listed as a Fentanyl overdose — which throws everyone into panic mode and forces the Club to split its attention.

The Club eventually focuses on Bogdan. Elizabeth (Mirren's character) has been working undercover at one point, introduced herself as 'Marina' to Bogdan, and later finds him playing chess with her husband Stephen. Bogdan drags Elizabeth to the cemetery and shows her bones that had been buried on top of a coffin years earlier. Those remains turn out to be a man named Peter Mercer.

Back at Elizabeth's flat, Bogdan confesses — on tape — to killing Tony. He claims it was an accident: he was trying to retrieve his passport from Tony (the film introduces a new plotline about Tony and others withholding passports from migrant workers), Tony fought back, and Bogdan killed him in the struggle. Stephen, who records his chess games, has the confession on tape, which nails Bogdan. He also denies poisoning Stephen and insists he didn’t mean to kill Tony.

Ian Ventham and Peter Mercer

Those two deaths are connected to a separate old crime. Elizabeth digs into past files and notices something odd: Penny, a former Thursday Murder Club member who is now in a coma, had never suggested a certain cold case when she was active — and that case involved Peter Mercer. Elizabeth reads the old notes and realizes Peter had actually murdered his girlfriend years ago, and Penny, knowing this, took matters into her own hands and killed him, burying the body with John’s help.

John, Penny’s husband, admits everything to Elizabeth and also reveals he killed Ian Ventham by dosing him with a huge amount of Fentanyl. Ian had been trying to dig up the grave and expose Penny and John, so John poisoned him to stop the grave-digging and protect his wife.

What happens to John and Penny?

Elizabeth says she will tell the police, but first gives John some time at Penny’s bedside. It becomes clear John will use that time to kill them both with the remaining Fentanyl. The film jumps forward to a funeral, where Ibrahim delivers a eulogy that frames John’s act as a tragic, love-driven choice: "Sometimes, good people do bad things. But what John did, he did for love. For the love of Penny."

Key cast (quick reference)

• Helen Mirren as Elizabeth — the Club's driving force
• Pierce Brosnan, Ben Kingsley, Celia Imrie — the other Club members
• David Tennant as Ian Ventham — Tony's former business partner
• Henry Lloyd-Hughes as Bogdan — former employee, later revealed to have killed Tony
• Naomi Ackie as Donna De Freitas — junior cop who helps the gang
• Daniel Mays as DCI Chris Hudson — Donna's annoyed superior
• Tony Curran — the property developer whose death kicks the plot off

How the movie changes the book (the important bits)

The film keeps the broad bones of Osman’s first Thursday Murder Club novel, but it trims and reworks a lot of the subplotting and motivations. Biggest changes to note:

1. The film invents a passport/illegal-worker angle to explain Bogdan’s motive: he was trying to get his passport back and killed Tony accidentally. In the book, Bogdan's motive is far darker and tied to a past shooting, £100k in stolen money and revenge connected to organised crime (Turkish Gianni, a murdered taxi driver, and a Cyprus thread). That entire criminal subplot is cut from the movie.
2. Bogdan is still the killer in both versions, but his role and backstory are simplified for the film.
3. The Peter Mercer storyline is condensed and some ancillary characters and plot threads (like Gordon and Karen Playfair, and a larger role for Father Mackie) are removed — the movie streamlines the mystery to keep it tighter on-screen.

Richard Osman on adapting his book

"The plot, as I understand it, for The Thursday Murder Club movie is based on the first book but it's not entirely the same, because you have to change things, is the truth," Osman said. "To have me looking over their shoulder every five seconds telling them that they couldn't do this or they couldn't do that I think would be hard."

He also mentioned that some producers had wanted full creative control over the script, and that wasn't the arrangement he went for — which helps explain why the film’s plot diverges from the book in places.

Where to watch

The Thursday Murder Club had a limited cinema run in the UK and is streaming on Netflix from Thursday 28 August 2025.

Bottom line: if you liked the cozy ensemble and sharp banter in Osman’s book, the movie gives you that plus a cleaner, more screen-friendly mystery. If you want all the nasty, knotty original motives and criminal backstory, you’ll need the novel.