Seeing isn’t believing in this diabolically clever tale of poisoning first published in the U.S. as The Problem of the Green Capsule in 1939.
Weeks after someone in the village of Sodbury Cross has added strychnine to some chocolate creams in a sweet shop, killing one child and sickening several others, wealthy peach grower Marcus Chesney, convinced that eyewitnesses to anything are unreliable, stages a brief midnight scene designed both to present his theory of the poisoning and to pull the wool over the eyes of his own three witnesses: Marjorie Wills, his niece and unofficial ward; George Harding, the suitor she met during a recent trip abroad; and Gilbert Ingram, a retired professor of psychology. Before any of them has a chance to start writing down answers to the 10 apparently innocent questions Marcus has asked them about the theater piece they’ve just seen, Marcus keels over, poisoned by a cyanide-filled capsule his unidentified co-star popped into his mouth just before the lights came up. Marcus’ brother, Dr. Joe Chesney, returns from a late-night house call just in time to pronounce him dead; Wilbur Emmet, the manager of Marcus’ nurseries and the man most likely to have been Marcus’ accomplice and assassin, lies unconscious in the yard outside. The three witnesses contradict each other about absolutely everything, but the biggest surprise awaits the moment that the ever-reliable Dr. Gideon Fell, on whom baffled DI Andrew Elliot calls for help, shows the witnesses the film that Marcus had asked George to make of what turned out to be his very last moments.
Of all Carr’s many celebrated puzzles, this one most closely resembles a magic trick. Be prepared to be royally hoodwinked.