The Fatal Garden — John Rhode

When Pauline Clobury is found murdered in the dark and the rain near the gate of Prior's Farm, suspicion centers on her young husband whom she plans to divorce. But when a new development occurs at the greenhouse of the same estate, both Superintendent James Waghorn, of New Scotland Yard's CID, and his friend, the veteran Dr. Priestley, decide to visit the scene. What they discover in the formal gardens leads the way to a strange theory of the events and an entirely new twist to the investigation.
As usual, the plot of this Rhode story is daringly conceived and logically developed, and the story ends with a complete justification of that grand old man of detection, the venerable Dr. Lancelot Priestley.