JOHN DICKSON CARR. The Case of the Constant Suicides (1941).

A scene of comedy, set on a sleeper coach as it heads from London to Glasgow, marks a frothy start to this twin-locked-room adventure, featuring Dr. Gideon Fell. Although Carr’s humor often has the effect of pushing his work off the rails, the interplay here between two Scots scholars of Restoration history, one stubbornly male and one winningly female, recalls a well-oiled screwball romance from Hollywood’s golden age. Awaiting Alan Campbell and Kathryn Campbell in Scotland (they are cousins, but genetically at a decent remove from each other) is the puzzle of how a relative of theirs, Angus Campbell, tumbled to his death from a 60-foot-high tower window at the Castle of Shira, the family’s ancestral home. A massive bolt had sealed shut the chamber from which he plunged, so murder would appear to be out of the question. But Dr. Fell, within his gargantuan frame, harbors a doubt or two about the case. What about the animal carrier found under Angus’s bed, for example? Might a killer have smuggled in a creature fierce enough to make the old guy leap from the window in fright? Then Alec Forbes, a known enemy of Angus and an ideal murder suspect, dies in his securely locked cottage; ostensibly, he took his own life by hanging. Meanwhile, there’s a war on, even out on the highland moors, and curious circumstances involving blackout window screens and the watchful eyes of the Home Guard give Fell further reason to harbor doubt.

As is usual for Carr, variations on “what might have happened” outnumber candidates for “who might have done it,” and the identity of the guilty party comes into view less through artful detection than by process of elimination. Add in just enough comedy and just enough romance and just enough Scottish atmosphere, though—along with two clever impossible-crime solutions—and the upshot is one of the author’s most agreeable tales.