Nearly all the Detection Club rules are broken in this, Christie's worst book for some fifty years. Poirot faces a group of super-criminals: a fiendish Oriental (a la Fu Manchu), an American millionaire, a mad scientist ("mad-mad-mad with the madness of genius!"), and "the destroyer," who are behind all the world problems: "the world-wide unrest, the labour troubles that beset every nation, and the revolutions that break out in some," as well as Lenin and Trotsky, "mere puppets whose every action was dictated by another's brain." Their ultimate goal is, of course, to use a laser beam to take over the world. The bulk of the book concerns various loosely related cases (some of which, such as "A Chess Problem," are ingenious enough), but too many episodes are appropriate to a shilling shocker: e.g., Hastings, having refused a fiendish Oriental devil's order to lure Poirot into a trap on pain of death (with typical English understatement, "that Chinese devil meant business, I was sure of that. It was goodbye to the good old world."), capitulates when he learns that his wife will die by the Seventy Lingering Deaths. And so it gets sillier and sillier as it goes on, until, Poirot having died and come back from the dead as an imaginary twin brother, it ends with the Big Four blowing up the Dolomites in a mass suicide pact. Tripe.