Graham and Joan Bendix have apparently succeeded in making that eighth wonder of the modern world, a happy marriage. But into the middle of it drops a box of chocolates. Joan Bendix is killed by a poisoned box of liqueur chocolates that cannot have been intended for her. The police investigation reaches a dead end. Chief Inspector Moresby calls on Roger Sheringham and his Crimes Circle - six amateur but intrepid detectives - to consider the case. The evidence is laid before them and they take turns to offer a solution. Each is more convincing than the last, slowly filling in the pieces of the puzzle, until the dazzling conclusion.