Stuart Palmer 
Puzzle of the Pepper Tree [EPUB ebook] 

On vacation in California, the spinster sleuth stumbles onto the case of a man murdered in mid-air—“[Withers is] still one of the best” (Anthony Boucher).  Because of the fog, the man in the brown suit arrives five minutes late for the ferry to Catalina Island. If he wishes to reach his destination today, his only option is the Dragonfly, a twelve-seat prop plane that makes up in speed what it lacks in comfort. The ride is bumpy, and all of the passengers—including a honeymooning couple, a film producer, and a would-be adventuress—find themselves feeling queasy. But none react as badly as the man in the brown suit, who sweats, shakes, and screams, “I’m dying! I don’t want to die!”—and by the time they reach Catalina, he already has. Vacationing schoolmarm Hildegarde Withers notices the corpse when they’re taking it off the plane. An amateur sleuth with a nose for murder, it doesn’t take her long to deduce foul play. But which of the passengers was dastardly enough to commit murder in mid-air? The Puzzle of the Pepper Tree is part of the Hildegarde Withers Mysteries series, which also includes The Penguin Pool Murder and Murder on the Blackboard.