At the Coopers Chase retirement village, psychiatrist Ibrahim Arif, former trade union leader Ron Ritchie, and mysterious Elizabeth Best are members of the Thursday Murder Club (TMC), which meets weekly to discuss cold cases. They are soon joined by Joyce, a retired nurse and new resident, whose medical knowledge proves useful. The group currently is investigating a case once handled by Detective Inspector Penny Gray in 1973, who was a member of the club and now comatose in Cooper Chase's hospice, involving the unsolved murder of Angela Hughes. Police Constable Donna De Freitas, recently transferred from London, visits the village and strikes up a friendship with the TMC. She confides that her work feels tedious, so the club eagerly draws her into their investigations. Meanwhile, conflict brews over plans to redevelop Coopers Chase into luxury flats. One of the owners, Ian Ventham, pushes the project forward, while his partner Tony Curran opposes it, promising the residents that he will block the sale. Shortly afterwards, Tony is murdered in his own home, his house ransacked and the weapon missing. The TMC resolve to investigate. With Donna's help, they learn that local crime boss Bobby Tanner is secretly involved in the business but has long been thought to be dead after disappearing a few years earlier, and that Ron's son Jason once worked with Tony. Suspicion briefly falls on Ian, but he is soon ruled out. During a residents' protest, Ian himself collapses and dies from a
fentanyl overdose, leaving Tanner the apparent sole owner. Jason is arrested, though the evidence against him proves weak. Elizabeth develops a cautious friendship with Bogdan, a Polish handyman employed at the village. He discovers a grave containing a skeleton on top of the coffin, later identified as Peter Mercer, the man who was Angela's boyfriend decades earlier. Elizabeth also begins receiving threats, warning her to leave the matter alone. When Jason provides an alibi (an affair with Ian's estranged wife Gemma), the TMC turn their attention back to Tanner. Elizabeth and Donna discover that he has been trafficking migrants and seizing their passports, and, to their shock, Tony was his partner. Elizabeth confronts him and strikes a bargain: he is to keep Coopers Chase intact in return for her silence. She then realises that Bogdan was responsible for Tony's death. At the same time, Bogdan, while playing chess with Elizabeth's husband Stephen, confesses, after being pressed, that he killed Tony under pressure but unintentionally. His confession is secretly, and accidentally, recorded by Stephen, and he is arrested. He reveals he merely wanted his passport back so he could return to Poland to his sick mother. The truth about Angela's murder also emerges. The TMC deduce that Mercer killed her, but that Penny secretly took justice into her own hands by killing Mercer and concealing his body. As Ian's plans to redevelop Coopers Chase might have revealed Mercer's body, thereby implicating Penny, her husband John murdered him to protect her. Both Penny and John die soon after in hospice care (implied to be a murder–suicide from fentanyl overdosing). At their funeral, Elizabeth presents Penny's club necklace to Joyce, formally welcoming her as a full member of the TMC. With Coopers Chase up for sale, Joyce's daughter Joanna considers buying it. Life in the village quietly resumes, with friendships renewed and the club ready for whatever mystery may come next. ==Cast==