Letter Edged in Blackmail

While eating in a hotel restaurant, Mike spots a man take a package from a woman's table. Even though the package contains a necklace with a broken clasp as the man claimed, Mike smells foul play and traces the woman who left the box. When he arrives at her house, he learns that she was pushed down her stairs and badly injured. Investigating further, he discovers she is the victim of a vicious blackmailer.