The Thursday Murder Club by Richard Osman

Elizabeth, Ron, Ibrahim, and Joyce make up the Thursday Murder Club at the Coopers Chase Retirement Village. They meet in the Jigsaw Room under the pretense of discussing Japanese opera, figuring this will keep others away. When one of the owners of the retirement village, Tony Curran, is murdered, the group is thrilled to have real case to work on, rather than cold cases from the past. They also charm PC Donna De Freitas and DCI Chris Hudson to share information with them. The Thursday Murder Club is a humorous cozy that hopefully will become a series.