Season 4 begins with a drug-addled and deathly ill Frank reappearing. Meanwhile, Fiona cares for the household and works at Worldwide Cup with her boyfriend boss Mike Pratt, and attempts to connect with Debbie and Carl, who are dealing with the upheaval of their adolescent hormones.

Frank stalks his previously unseen daughter Sammi and is surprised to learn that she has a son. Meanwhile, Fiona and Mike get serious; and Carl steals dogs and holds them for ransom, so he can earn some drug money for Frank. Also: Sheila has her first successful online date with a Native American cowboy named Roger Running Tree.