Black CoffeeSugar and cream? Or a lethal dose of poison? The inventor of a powerful new explosive, Sir Claud Amory, is somewhat disconcerted when the chemical formula goes missing the situation worsened by the knowledge that the thief is one of Sir Clauds house guests. A relative? Or a friend? Whoever the culprit, Sir Claud decides to give them a sporting chance which is more than someone gives him. As the doors are locked and the lights turned off, rather than