The room was on the fourth floor, and the door was locked—with the key on the inside. The windows were closed and secured—from the inside. The chimney was too narrow for even a cat to fit through. How, then, did the murderer escape? And whose were the two angry voices the neighbors heard as they climbed the stairs? No one in Paris could find answers to this riddle. Except Auguste Dupin, who could see further and think more clearly than most. The answers to the mystery were there, but only a clever man could see them.