watch?v=p8-AKZcIyqEA CHAIN OF EVIDENCE, by Carolyn Wells - FULL AUDIOBOOKThe Mystery: ”Mr. Stone," I began, "if three persons spent the night in an apartment so securely locked on the inside that there was no possible means of ingress, and if in the morning it was found that one of those three persons had been murdered at midnight, would you say that the guilt must rest upon either one or both of the other two persons?” (Carolyn Wells )The solution - who knows? Listen and enjoy.