Perry Mason (1957) : 7x7

Gwynn Elston's best friend, Nell Grimes, asks her to move in with her due to the fact that Nell's husband, Felton, is often out of town on business. Gwynn, who has a door-to-door sales job, is then astonished to see Felton's picture in someone else's house where he's known as Frank Gillette. Felton, who's really a nasty mother, tries to poison Gwynn, when she confronts him but she survives and runs to Perry for help. Then Felton is found shot to death and things go from awful to good grief for poor Gwynn--she gets arrested for the crime.