This is possibly John Dickson Carr’s finest story. It’s definitely his funniest. There’s a murder, of course, but it happens offstage. In fact, much of the book concerns the protagonists’ attempt to prove that the murder even took place. It’s something like Hitchcock’s The Lady Vanishes, if it were rebooted as a musical comedy.

The classic closed room becomes, in this mystery, a closed ship–to be precise, an ocean liner on the high seas between New York and London. Somewhere aboard, possibly disguised, is an international thief and cold-blooded killer. On the side of the good guys is a motley group of friends including Henry Morgan (Dickson Carr’s mystery writer character), an American diplomat, his fiancee whose French father runs an acclaimed puppet show, and an eccentric Norwegian sea captain. Between bouts of sea-sickness they pursue a valuable statuette that keeps appearing and disappearing, drink oceans of champagne and whiskey, and cause the ship’s skipper headaches (both figurative and literal). Oh, and their offhand sleuthing eventually unmasks the murderer, although to clinch the deal they need the assistance of arch-detective Dr. Fell, who is not–to his own everlasting disappointment–even a passenger on the voyage.

A note on my book’s edition: it dates from 1934, and at that time Harper apparently put out a series of ‘sealed mysteries’–until you broke the seal, you couldn’t finish reading the story, and if you decided to bail out you could (theoretically, at least) return the book for a full refund. Here’s the challenge page from my book:

At the end of this book, there’s another intriguing offer. I wonder if Harper would still honor it today?