When Helen Mirren picked up cozy crime mystery novel The Thursday Murder Club, she couldn’t have known she’d end up playing retiree Elizabeth in the movie adaptation, streaming now on Netflix. But she did breeze through it just as fast as she could. Asks the award-winning actor, “It’s unputdownable, isn’t it?”

The Thursday Murder Club falls squarely within a perennially popular genre. “There’s a reason why Agatha Christie, P. D. James, Barbara Vine, and Patricia Highsmith continue to be read,” Mirren continues. “There is an enduring fascination with those sorts of murder mysteries. I think the great thing that Richard Osman did was to combine this wonderful humor with it.”

Both Osman’s bestselling book and the film, produced by Steven Spielberg and directed by Chris Columbus, follow a group of senior citizens who solve cold cases together in their titular club in the quant retirement community of Coopers Chase. That is, until a dead body turns up closer to home than they ever would have expected, and they team up with a local detective to help solve the murder. 

Steven Spielberg visits the sets of The Thursday Murder Club. (L to R) Sir Ben Kingsley, Helen Mirren, Steven Spielberg, Richard Osman, Chris Columbus, Celia Imrie, Pierce Brosnan

This murder mystery with heart requires a delicate balance to pull off. And making sure that the qualities that turned it into a bestseller (and spawned four sequels and counting) made it to the screen intact was a whole new achievement in itself. Retaining as much of the book’s charm as possible while keeping the plot propulsive was the biggest challenge for Columbus. In other words, how do you fit 400 pages into a two-hour runtime? 

“I love the book and I love the characters, so I wanted to remain as faithful as possible,” the director tells Tudum. “But there’s too much of the book to really be condensed in a film exactly as written. So we had to take some liberties in terms of the murder, and the plot, and some of the red herrings that exist in Richard Osman’s book.”

Sir Ben Kingsley as Ibrahim Arif, Pierce Brosnan as Ron Ritchie, Author Richard Osman, Helen Mirren as Elizabeth Best, Celia Imrie as Joyce Meadowcroft

That’s when it helps to have the author himself on board. Columbus credits Osman for being “generous with his time” and answering the filmmaking team’s many questions. To hear Osman tell it, however, the author remained as hands-off as possible. “You must either be completely involved or not involved at all,” he says. “I’ve got this incredible director — Chris Columbus — this incredible cast, and I just let them get on with it. The film is a different thing to the book, and you have to let it be. To me, this is an entirely different undertaking than the book.”

Imrie knows that eagle-eyed viewers will be searching for clues Osman peppered throughout his book that plenty of them have made it to the screen. “We can’t stuff them all in, but they are marvelous,” she says.

But while changes were inevitable, one nonnegotiable was that the beautifully fleshed-out characters — people of a certain age, who are often ignored in their everyday lives — truly came to life in the new medium. 

Osman knows the structure of a typical crime story is always the same: Someone is killed; at first, you don’t know who did it, then eventually you find out. But that’s also what makes the genre so fun for him. “To me, whodunits, it’s never about what happens,” he says. “It’s all about, ‘Why do I care what happens?’ That’s all that matters, and that’s all character. It is never, ‘Oh, that’s a clever plot,’ or, ‘That’s a plot twist.’ Have all of those, by all means, but unless you care about the characters, you can have 50 twists and it doesn’t matter.”

Naomi Ackie, who plays the club’s ally on the police force, PC Donna De Freitas, focused on translating her character’s internal thoughts, which we’re able to read on the page, into behavior we can see on the screen. It was important to retain, and develop, the real essence of her character. 

“What I really got from the book is how ballsy she is,” the actor says. “She’s got guts. She wants to succeed; she wants to get better. She’s frustrated, and this is her way of working her way out of the situation that she’s already in.”

Pierce Brosnan read the book after he was cast, but immediately connected with former trade union activist Ron. “I love the humor of Ron. I love the humanity of Ron,” he says. “He's a rather stubborn personality, like a bull in a china shop at times. He was a trade unionist, union man. A nurturer, really, and a giver who looks after the working man, the working woman. He wants the right thing by the people and wants to poke it in the eye to the man.”

Despite the character through lines, some specifics had to change for the purposes of movie magic. Although the club’s meeting space is described as a four-walled room somewhere deep within the Coopers Chase building, production designer James Merifield knew that his version would move the action to a beautiful old orangery with windows overlooking the property. Now you can see fellow residents playing lawn games, being pushed in wheelchairs, and exploring their beautiful estate. 

Then there’s the plot itself. Producer Jennifer Todd confirms that the complicated, decades-spanning mysteries in the series’ first book were simplified to make them more digestible in the film. But the heart of Osman’s series — the characters — are all still there. 

“It’s important to tell stories about people in this place in their life and showing them to be relevant and adventurous and still having fun,” Todd tells Tudum. “It was such a delicious read for that, and just felt like it should be a movie.” And now it is.

The Thursday Murder Club is now streaming on Netflix, and the fifth book in Osman’s series, The Impossible Fortune, is out Sept. 30.