Hushed in death / Stephen Kelly.

Enhanced descriptions from Syndetics:

In the third volume of the Inspector Lamb mystery series, a murder at a hospital for veterans in rural England leaves Lamb with a village full of suspects, each with a motive and secrets of their own.

In the spring of 1942, with the war in Europe raging, a gruesome murder shocks the rural community of Marbury, where a once-grand estate called Elton House has been transformed into a hospital for "shell-shocked" officers sent back from the front lines. When Detective Chief Inspector Lamb arrives to solve the case, he quickly learns that the victim, Elton House's gardener Joseph Lee, had plenty of enemies in Marbury--and so he and his team have plenty of suspects.

Along with his team of investigators, which includes his daughter Vera, Lamb begins to untangle the threads of rivalry and deceit that lie beneath the surface of the seemingly-peaceful countryside village. It soon becomes clear that Lee's mysterious past is intertwined with the history of Elton House itself, which fell into disrepair a generation earlier after a shockingly similar murder, and the mystery deepens further when Lamb discovers that one of the prime suspects has seemingly committed suicide.

As Lamb pieces together the connections between the crimes of the present and those of the past, he must dive into the darkest, most secret corners of Elton House to discover who is committing murder, and why.