From The Perry Mason TV Show Book (Revised)
Felton Grimes doesn’t have both oars in the water, or so his wife’s best friend, Gwynn Elston, thinks. It seems that the oddball Felton is often out of town on business, so much so that his wife Nell has asked Gwynn to move in with her. Gwynn does so and soon likes her new home and her job selling encyclopedias door to door.

But she doesn’t like Felton. When he’s home, he’s constantly trying to put the move on Gwynn. One day on the job, Gwynn is astonished to see Felton's picture in someone else's house. Not only that, but to the Gillette family, Felton Grimes is Frank Gillette, husband and father. Then Felton, or whatever his real name is, tries to poison Gwynn. It’s a close shave, but she survives. She sees Perry for advice. It’s a good thing, too. Because when Felton is found shot to death, the police arrest Gwynn for the crime.