When Perry Mason and Paul Drake ran the ad, all they were hoping for was a clue to the identity of a hit-and-run driver. The first reply looked suspicious. It said that the license number of the wanted car was written down in the notebook of a woman who could be out of her apartment from two to five on a certain afternoon, and a key to the apartment was enclosed.
"Could this letter," Mason asked Della Street, "have been written by the woman herself? I want to get the feminine angle." Della laughed. "There aren't any feminine angles - they're all curved." Fast curves.
From the very first time Perry met the voluptuous blonde, Lucille Barton, she pitched him trouble. She lied about her past, about her many marriages, about her gun, and about her boyfriends. Then the murders began. And the cops turned up with evidence which pointed clearly to one person as the killer - Perry Mason!