Welcome to retirement. So, are you ready to catch your first killer?

Ever since Miss Marple picked up her knitting needles, sleuths of a certain age have been genteelly wrangling killers while being ignored by the young folks. But “The Thursday Murder Club” has helped launch a trend of golden-age detectives not seen since Jessica Fletcher last parked her bike in Cabot Cove, Maine.

While catching killers rather than putting together jigsaw puzzles has become the hot new hobby for fictional retirees, these books are also showing people in their 70s and 80s as vibrant, brave, and clever. 

The “Thursday Murder Club” series, by Richard Osman, about a quartet of septuagenarian sleuths, has sold more than 10 million copies worldwide. Oscar-winners Helen Mirren and Ben Kingsley and former James Bond Pierce Brosnan have all signed in to the Coopers Chase Retirement Village to star in the movie version.

While some authors play with ageism tropes to deadly effect – see Deanna Raybourn’s “Killers of a Certain Age” (no really, you should read it) – others like Mr. Osman take on diagnoses like Alzheimer’s while writing fully realized characters who maintain their agency and humanity. Or, think of Walter Mosley’s masterful telling of a cantankerous 91-year-old suffering from dementia in “The Last Days of Ptolemy Grey.” With the help of an experimental drug, Ptolemy lives his last days with the vigor of a younger man and a memory to match, which helps him piece together his nephew’s murder.

Sometimes writers paint heroes grappling with mental health diagnoses, like the aforementioned memory loss, or with physical limitations. And they also amplify traits like experience, intelligence, and mental resolve – the flip side to physical decline. This offers readers new ways to view aging, experts say.

Carsten Koall/picture-alliance/dpa/AP/File

Richard Osman, English author, television presenter, and producer, poses at a get-together for the launch of his book, “The Thursday Murder Club,” in Berlin, in June 2022.

“These are the conversations about the incredible heterogeneity of old age,” says Erin Lamb, associate professor of bioethics in the Case Western Reserve University School of Medicine. She studies and teaches about aging. Dr. Lamb says that what is important to understand is that while many people choose to ignore older people and lean into stereotypes that portray them as invisible, that isn’t true of older people’s reality.

“We grow more and more diverse as we grow older, because of our life experiences, and so all of these [stories] that begin to get to the complexity or begin to ask new questions, at least we’re treating older people like they are people,” Dr. Lamb says.

In 2019, the British media forum Gransnet did a survey on ageism in fiction of more than 1,000 women over 40 years old. More than half said they felt older women in fiction had clichéd roles, and almost half of them said that there weren’t enough books about middle-aged or older women. These same women reported that they felt insulted by tropes of older female characters being baffled by technology, especially since some 75% of those surveyed used technology to purchase the books they read. They wanted to see older women working, more active, and going places that they would like to travel. A majority of those surveyed read for enjoyment.

When feminist writer Betty Friedan wrote “The Fountain of Age” in 1993, she did a survey of images of older people that she did and didn’t see in magazines. The images she saw were invariably of age – and older people themselves – as a problem.

Ms. Friedan wrote, “On the one hand, despite continued reports of advances in our life expectancy, there was a curious absence – in effect, a blackout – of images of people over sixty-five, especially older women, doing, or even selling, anything at all in the mass media. On the other hand, there was an increasing obsession with the problem of age and how to avoid it personally, through diet, exercise, chemical formulas, plastic surgery, moisturizing creams, psychological defenses, and outright denial – as early and as long as possible.”

In Robert Thorogood’s “The Marlow Murder Club” series, he turns the trope of people feebly wasting away in nursing homes on its head with a witty protagonist, Judith Potts. Judith is a 78-year-old crossword puzzle specialist who occasionally skinny-dips in the Thames. Her neighbor is murdered, and she uses her unrelenting curiosity to find his killer. She recruits a vicar’s wife and a dog walker as part of her team. The novel, which inspired a TV series coming to PBS’s “Masterpiece,” was followed by “Death Comes to Marlow” and “The Queen of Poisons.” Mr. Thorogood, interviewed via a video call from his home in Marlow, England, says that the next book will be out in early 2025.

“We have lots of men who solve murder mystery crimes. It would be exciting for me to have a woman lead up a murder mystery,” Mr. Thorogood says of his initial thoughts during the creative process.

He envisioned something in the realm of Miss Marple. His inspiration for Judith and her gang of crime solvers? His grandma, Betty, and his great-aunts, all of whom lived colorful lives. (Although one aunt, Jess, wouldn’t let him put vegetables of the same color next to each other on his dinner plate.)

“They were these amazing, really inspirational, bright women,” he says. “They were cleverer than their husbands, but the husbands had status and went off and had jobs and they wore suits,” Mr. Thorogood continues. His answer was an older, independently wealthy, single sleuth who would outsmart the men and had no interest in ever getting married.

He took that to his publisher, and “Marlow Murders” was born. 

The process was the complete opposite for Deanna Raybourn. Her “Killers of a Certain Age” transports readers to foreign countries with four 60-year-old retired assassins, whose former employer is trying to kill them. While they don’t have the physical strength of their youth, they have experience, wisdom, and a lifetime of spy craft to fall back on.

“The whole thing started with my publisher,” Ms. Raybourn says in a phone interview. From high up in the company, the question was asked: Why don’t they lean into older women doing cool things?

“They were sitting around having a chat and they said, ‘OK, who could we get to write a book like that?’ And everybody at the table said my name at the same time,” she laughs.

Ms. Raybourn, author of the Veronica Speedwell mysteries, agreed to write the novel on two conditions: The women needed to be assassins, and the book needed to be set in contemporary times, as opposed to a period piece. Ms. Raybourn credits publishers being hungry for more books like hers to a cultural shift brought on by everyday older people who have forced society to alter its view of them.

“I think that we’re pushing the needle because of that,” Ms. Raybourn says. People take better care of themselves, which has created a new picture about older people, and that more vigorous portrait has been amplified by the media, she says.

“Now we’re saying, ‘Let’s not just show somebody being healthy and vibrant and active in their 60s, 70s, and 80s and beyond, let’s show a broader picture of that,’” Ms. Raybourn says.