The Last Devil to Die (2023) is a cozy murder mystery novel by Richard Osman. It is the fourth book in Osman’s Thursday Murder Club series, which follows a group of pensioners living in a retirement community in South England who meet each week to solve mysteries. The group often have a connection to their cases, sometimes personal and sometimes geographical, and they tend to uncover ancillary mysteries throughout their investigations. The preceding three books in the series are The Thursday Murder Club (2020), The Man Who Died Twice (2021), and The Bullet That Missed (2022).

The primary mystery in The Last Devil to Die involves the murder of Kuldesh Sharma, a minor character introduced in the series’ third installment, The Bullet That Missed (2022). Other mysteries in the novel include a missing shipment of heroin, a case of potential catfishing, subsequent murders, and secrets among the main characters.

More than any of its predecessors, The Last Devil to Die focuses on the physical considerations of being an amateur detective in old age. Correspondingly, the book’s thematic considerations include The Resilience and Resourcefulness of Elderly Individuals, The Exploration of Friendship and Camaraderie Among Retirees, The Challenges and Dangers of Getting Involved in Criminal Investigations, and The Impact of Aging, Dementia, and Mortality. This last theme in particular sets this novel apart from the prior three books. While the realities of aging have always been an element of the series, it takes a prominent place in this installment.

This study guide references the 2023 edition published by Pamela Dorman/Viking, an imprint of Penguin Books.

Content Warning: This guide mentions assisted suicide, which is a plot point in the novel.

Plot Summary

The Last Devil to Die begins with a prologue depicting the final moments of elderly antiques dealer Kuldesh Sharma, who first appeared in Osman’s The Bullet That Missed (See: Background). Late on December 27, Kuldesh goes to meet someone to discuss a box left in his shop. Before he can get out of his car, he is shot in the head. The identity of Kuldesh’s murderer and the location of the box, now missing, comprise the novel’s main mysteries.

The Thursday Murder Club includes ex-spy Elizabeth Best, retired nurse Joyce Meadowcroft, retired psychiatrist Ibrahim Arif, and former union activist Ron Richie. Kuldesh was the friend of Elizabeth’s husband Stephen, meaning the club has a personal interest in solving his murder case. Before the club members learn about Kuldesh’s death, however, they embark on a separate case involving Mervyn, another resident of their retirement community, Coopers Chase; Mervyn is being catfished by an online fraudster.

The box that Kuldesh was killed over contains a shipment of heroin that was smuggled into the country by a man named Mitch Maxwell. Dominic “Dom” Holt, Mitch’s second-in-command, used Kuldesh’s shop as a drop point because it was the only antiques shop open the day after Christmas. Kuldesh was sold the box for £50 and told that someone would be in the following day to buy the box for £500, a not-uncommon occurrence in the antiques world. Kuldesh decided to hide the box, however, and then was killed.

Kuldesh’s body is found on New Year’s morning. Stephen and Elizabeth learn about Kuldesh’s murder through a man named Bogdan, the boyfriend of Donna De Freitas, a police officer. Despite Stephen’s dementia, he seems to remember seeing Kuldesh recently. Bogdan shares that Kuldesh’s shop was broken into after the shooting, and Elizabeth decides to visit the shop with Joyce.

While Donna and her partner, Chris Hudson, search Kuldesh’s ransacked shop, Donna finds a cell phone behind a radiator, but she doesn’t turn it into evidence. Elizabeth and Joyce arrive, but when they aren’t allowed to search for clues, they head to a nearby café to check its CCTV footage, which shows Dominic Holt visiting Kuldesh.

On January 4, Chris and Donna’s case is taken over by Senior Investigating Officer (SIO) Jill Regan of the National Crime Agency, who asks Chris and Donna to stop investigating. At Kuldesh’s funeral, the gang exchanges information with Chris and Donna and learns from the only other attendee, Big Dave, that Kuldesh purchased a shovel shortly before his death.

When Elizabeth arrives home from the funeral, Stephen is sitting at his office desk. He has received a letter, which he reads to Elizabeth, from someone who suspects he has dementia. The letter is from himself, and it makes Elizabeth promise to read it to him every day.

As Part 2 begins, Ron, Ibrahim, Joyce, and Elizabeth are staking out Dom’s warehouse. Dom threatens them, slashing their car’s tires and smashing the windshield. Next, Elizabeth and Joyce visit Nina Mishra, a professor of historical archaeology. Kuldesh called her the day of his murder, saying he needed help with something without explaining further. According to Nina, Kuldesh had a lock-up where he stored questionable items. She and her boss, Jonjo, suggest that if he was looking to sell the heroin, his other call may have been to antiques dealer and art forger Samantha Barnes.

Elizabeth calls Samantha to ask if Samantha knew Kuldesh or anything about heroin. She mentions that Joyce and Ibrahim will be visiting soon. Meanwhile, Ron and Ibrahim recruit Bob, a retired computer expert, to help them trap the person catfishing Mervyn, who has been asking for more money.

That evening, Mitch breaks into Ron’s apartment and attacks him. Mitch suspects Kuldesh gave Ron the heroin before he was killed. Ron denies this and calls the gang. Elizabeth, Ibrahim, and Joyce come over, and they all discuss the case with Mitch.

Soon after, Elizabeth and Stephen travel to London to meet with Viktor, a former Soviet spy whom Elizabeth knows professionally. Elizabeth has asked Viktor to talk to Stephen about his dementia. Stephen explains what he is going through and says he is in a great deal of pain.

Meanwhile, Ibrahim and Joyce visit Samantha and her husband, Garth. Though they learn little, Joyce suspects that Samantha and Garth know more than they’re telling and that they will meet again.

Determined to keep working the case, Chris breaks into Dom’s warehouse only to find that Dom was recently murdered. He calls Ron and Joyce and has them claim to have heard a gunshot and phone him. While Ron and Joyce wait for the official police to arrive, they take photos of the body. While they’re preoccupied with Dom’s murder, Garth breaks into Joyce’s apartment, but he is gone before they arrive back to view the crime scene photos they took. The gang decides to organize a Sunday lunch at Coopers Chase so everyone involved can openly discuss the case.

Meanwhile, Bogdan visits with Stephen, who is concerned because Snowy, the local fox who hangs around Coopers Chase, is missing. They search for him, and Stephen spots a small mound in the snow. It turns out to be Snowy, who has died. They agree to bury him in the morning. Joyce later writes about Snowy’s burial in her diary. She mentions how many residents attended, including Stephen, whom she assumes came to say goodbye to everyone.

Joyce, Elizabeth, and Nina visit Kuldesh’s lockup but don’t find the heroin or any clues. Later they meet with Mitch and his partner, Luca Buttaci, as well as Samantha and Garth, to discuss the case. They let slip that Kuldesh had a lock-up, knowing that only those who do not have the heroin will go to search it. Chris and Donna stake out the lock-up on behalf of the Thursday Murder Club. Mitch and Luca arrive to search it, but they don’t find anything. Meanwhile, someone attacks Samantha in her home, killing her.

At their home, Elizabeth and Stephen talk about time, memory, and their life together. Stephen has injected himself with something he got from Viktor and is going to die soon. Elizabeth strokes his hair until he stops breathing. He is cremated a few days later. Late that same night, unable to sleep, Elizabeth has a revelation about the case while thinking about Stephen. She realizes that Kuldesh must have called Stephen and that the heroin box is likely buried in the allotment in Coopers Chase.

Part 3 begins with the Thursday Murder Club outside with Bogdan, who is digging in the allotment. He finds the box with the heroin, and they concoct a plan to let everyone know they have it. Ibrahim lets his patient, drug dealer Connie Johnson, know that they found it, presuming she will spread the news.

Elsewhere, Mitch, Luca, and Garth meet atop a car park at Garth’s request. Believing Luca either killed his wife or is working for the cops, Garth throws Luca off the car park to his death. He and Mitch then head to Coopers Chase to retrieve the heroin.

Jeremmy, the man who has been catfishing Mervyn, is also on his way to Coopers Chase—part of Joyce’s plan to wrap up all their cases at once. While they’re waiting for everyone to arrive, Ibrahim and Computer Bob discuss Ibrahim’s past, and Ibrahim shares things he’s never told anyone.

Jeremmy arrives, and the gang makes him an offer. They ask him to sell the heroin for them, and he agrees. When he leaves with the heroin, Donna meets him outside the door to arrest him. After Donna has taken possession of the heroin, Garth and Mitch arrive looking for it. They threaten the gang, but Joyce says the heroin is already gone.

Garth explains that all this trouble was never about the heroin but about the box itself, which is 6,000 years old and worth significantly more than the heroin. Mitch demands the box, but Joyce says she threw it away because it smelled funky. He rushes to the dump to look for it.

Elizabeth takes the box to the university for authentication. She explains to Nina’s boss, Jonjo, how the box was smuggled in by heroin dealers. She asks Jonjo for a favor: She wants to send it back to Baghdad where it belongs, but with Stephen’s ashes inside it, as that is what he would have wanted. Jonjo agrees despite his initial hesitation. As they discuss this, a fire alarm goes off. They leave the box in Jonjo’s office, but it’s gone when they return. This is as Elizabeth intended; she has set up Kuldesh’s killer.

Sometime later, Garth meets Nina at a motorway station, part of the trap set by Elizabeth that Garth agreed to take part in because they believe that Kuldesh’s killer—Nina—also killed Samantha. Nina shows Garth the box, which she believes he will purchase from her. Instead, Elizabeth and the rest of the gang confront Nina, and Nina is eventually arrested. Not far away, Mitch has a heart attack and dies while searching through the dump for the box.

Later, Connie Johnson emails her hitwoman to let her know Luca is already dead, so there is no need to kill him. Connie also ordered the murders of Dominic and Samantha as part of a plan to take over the local heroin trade.

The club remains ignorant of Connie’s part in the novel’s events. In the final chapter, Joyce reveals that the box with Stephen’s ashes is now in Baghdad, where Elizabeth will soon visit.