No Flowers, by Request — June Thomson

Detective Chief Inspector Rudd is faced with the murder of young, successful lawyer David Hamilton, husband of beautiful, much-admired Elizabeth Napier and son-in-law of Felix Napier, recent widower, who adores his daughter, lives nearby and had sold his highly respected kennels to rough-edged Steven Bradley.

Returning with Elizabeth to her house one rainy night after she'd called him to help with a flat tire, Felix finds David shot to death in the library. Everything points to an intruder, but the more Rudd explores, the more doubtful he grows. When evidence is uncovered indicating that the serenity of the Hamilton household was a well-built facade, things begin to fall into place, and a tiny mistake by the murderer brings an ending with an air of inevitable tragedy.