Murder of a Lady is a classic locked door mystery set in a castle in Scotland next to a loch. Amateur sleuth Dr. Eustace Hailey is visiting in the area when he hears of the death of Miss Mary Gregor, whom some regard as a saint, the respected sister of Duchlan, the castle owner. She was found dead in her bedroom of a stab would, but the bedroom door was locked. No one could have entered the window, because men were fishing in the loch, and the window was in plain sight of their boats. Miss Gregor is found to have an old wound in her chest that no one admits to knowing about.
When Dr. Hailey goes to investigate, he is not welcomed by Inspector Dundas, who wants to solve the case himself. An oddity of it was that a herring scale was found on the victim, and this and the report of a splash are enough to start rumors of a selkie among the Highland servants. Dundas is able to make no headway in the case at all, though, and finally asks for Dr. Hailey’s help. But shortly after the doctor arrives, Dundas is himself murdered, in similar circumstances to the original murder, within seconds of Hailey and Dr. McDonald leaving his room.
The new policeman, Inspector Barley, is quick to decide that Miss Gregor was murdered by Oonagh, Duchlan’s son’s wife, and Dr. McGregor, whom he thinks are lovers. He and Dr. Hailey have realized that Oonagh was trapped in a horrible situation at the castle, in a rivalry with Miss Gregor, who was not as saintly as people believe. But Dr. Hailey believes that Oonagh loves her husband Eoghan and is not having an affair. And soon there is another murder.
This novel is certainly a characteristic Golden Ager, focusing most of its attention on the locked room puzzle, although some attention also goes to understanding the psychology of the people living in the house. Still, Dr. Hailey is an enigma, and the story is wrapped up so abruptly after the solution of the murder that it is startling. Still, I mildly enjoyed this novel, especially for its Highland background.