It's Always Sunny in Philadelphia: Season 2, Episode 10

2 - 10: Dennis and Dee Get a New Dad

Dee receives e-mails from a man who claims to be her father (Stephen Collins), so she confronts Frank and Barbara (Danny DeVito and Anne Archer) to find out what's up. Meanwhile, Mac seeks out his own dad (Gregory Scott Cummins), who's in prison. Mrs. Kelly: Lynne Marie Stewart.