Robbie's father Ed Palmer, a deadbeat who left the boys very young, turns up and slickly gets free board, next convinces his boy to move out and rent a room together. Eric perseveres to make Robbie realize he can't waste his future on a super-dad that never existed, as his very imperfect mother always claimed. Simon's social life clashes badly with parental essay standard demands. Matt is furious to find Ruthie lied to use him in willful disobedience. Lucy hangs out with classmate Ashley's 'cool' mother Serena, only to find a 'regular' mother is better.

Robbie wonders why Matt is suddenly so friendly, ignoring it's because Matt dates his ex Cheryl, who wants him to tell Robbie but doesn't push that, while Robbie spontaneously tells he studies a course with Heather, who needs his help. Simon feels a social outcast when nicknamed 'virgin Camden' because his mother assured Sasha's blabbermouth ma he's sexually inactive, but actually schoolgirls line up to date him. Viciously jealous, Annie meanly forces Eric to give up counseling Serena, yet denies that's her doing and sticks to her guns after Ruthie commends her as bitchy selfishness-model.

Robbie panics when Mary announces she's returning for the summer months, so he tells her to follow parental instructions not to date her all that time. Mike inspires Lucy how to stay with Jeremy now he's accepted to Juliard: marriage, so they get engaged. Matt is dumped by Cheryl for not telling the family about them, but that gives him the courage and more reward then he bargained for. Wilson was dumped but traveled all the way home, just when Mary's claim of sexual intimacy with Jeremy make Robbie deck Lucy's equally startled fiancé. Simon and Tim discover Deena dated each of them behind the other's back. Serena abuses her lonely birthday to make a move on therapist Eric, while hardware shopkeeper James Carver courts long-oblivious Annie.

Robbie gathers the courage to tell Mary openly, now her lies are exposed, their relationship is over, staying with the family his priority. Simon nurses his broken heart on account of Deenah, refusing to become 'just friends' again. Wilson bonds, while bunking, with Matt and Robby, and demands for Mary to return and go steady in New York, or break up completely. Jeremy forgives Lucy for doubting her fiancé's fidelity. Ultimately Eric helps her transfer to his New York alma mater, near Juliard. The Camden parents finally realize Serena and James are seducing them, ward off each suitor and match the lonely hearts.

Robbie introduces Lucy to his friend Hugh, feeling she should date again, but gets jealous enough to separate them with lies. Matt stands up against the free clinic's staff and gets Hank to overrule Dr. Kent's diagnose-and-operate routine. Feeling incompetent as a waiter at Pete's Simon resigns, but he gets promoted because of his business-planning skills. Cued by Billy via George, Wilson and Mary (who is failing in firefighter training) realize it's time to decide whether to commit to becoming a family.