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 would 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 gets the feminine angle.”