Jim Hanvey is a genial but top-notch detective who has retired to his country home. An insurance company hires him to find a missing emerald so they won't have to pay out the $100,000 for which the jewel is insured. It doesn't take him long to find the emerald, but he discovers that finding it was the easy part; the difficult part is getting it back to its rightful owner, and he winds up involved in a murder in which an innocent man is framed.

Schlitz is a tourist in the White Mountains of New Hampshire. Ignoring posted warnings which say that you shouldn't climb Mount Washington (the tallest mountain in New England) in bad weather, Schlitz pushes onward up the mountain, briefcase in hand. He gets lost in the snow, becomes entangled in mischief spun by a quirky hermit, and finally ends up skiing down Tuckerman's Ravine at perilous speeds, losing his briefcase several times.

In a spooky hotel on the coast of France, two bands of crooks are working independently of the other in an attempt to steal the inherited fortune of an American girl, Sue Tally. Along the way the heiress is kidnapped, three murders are committed, a girl appears in two places at once, mysterious persons roam about the old hotel at night and mysteriously disappear, and there is a hidden room without any doors.

A French sleuth in England helps the police solve a series of murders linked by the diary pages of a dead woman.