A 'cool' schoolmate slips Matt a joint, which he politely tucks away in his shirt-pocket but accidentally loses the marijuana at home, where dad finds it dropping from Happy's jaw. Annie stops him from accusing Matt without any proof, so they agree to probe the kids individually, and their guests, even Wilson, who contrasts brilliantly with Lucy's Goth new mate Rod. Hasty hiding the evidence causes a huge misunderstanding. Annie's confession, first to Eric, then to Matt, she once 'experimented' too, backfires. Simon, exhausted from trying to teach Ruthie laundry, is furious when Matt confesses to spare his siblings drug tests. Eric's deaf rage only drives Matt away, and both men near despair, yet providence seems to intervene.

Simon and Ruthie's hope to keep the pair of 'pet' lizards a classmate of her offered for free are frustrated. Jimmy Moon has dumped his girl, so Lucy hopes to get him back at last, but 'biker' Rod decides it's time to make his move too. Matt and Mary coach different suitors, while Simon takes betting scores. Eric's group session for couples who married the last year starts bored, but soon unleashes frustrations with all of them. He brings Annie along as 'good example', but her surprise-visiting pa's offer to have them buried alongside him causes frictions in their own marriage.

Matt is edgy, telling only his sibling he found an out of state summer job so he'll leave home in days, not months. Simon finds a brilliant trick to train happy for a TV pet food commercial, but there's a stage-fright complication. Mary rudely scolds Matt, unlike Wilson who leaves diplomatically, for getting physical at home, but her doctor notifies she's pregnant. Lucy cruelly keeps suitors Jimmy and Rod, who both chose Eric as career day model, dangling, but Wilson, who appreciates her help with Billie, arranges a date with Kenny, whom she may really want.

Matt worries now he's about to leave home, as self-absorbed, phone-glued Mary hasn't even got a clue what's happening with their younger siblings, nor is any use for either. Simon is heart-broken when Happy's original family head Jack Martin turns up and returns with a lawyer to claim the dog back. Eric considers his parents's surprise visit awkward and pointless as Matt won't be around to hold his valedictorian speech. The colonel however takes charge of an operation dog rescue inspired by Jimmy and Rod. Those two also undo Lucy's idiotic dumping of Kenny for being 'too perfect to be interested in her' and hold a remarkable church sermon. Matt changes his plans after a call from the colonel, learning about it and Annie's confession that Mary's pregnancy diagnosis got mixed up with her real one.

Simon wants to buy the perfect gift for Deena; Lucy's ex-boyfriend is spending time at the Camden's home; Heather is engaged.

Simon is in absurd trouble just because his mother and the principal make a huge drama of a finger-gesture among schoolboys. Matt tries to explain, but Simon feels he's robbed of another part of his childish innocence. Matt wrestles with domestic problems among his roommates and considers moving back home on account of Eric's cardiac condition. Basketball coach Jason Cleary decides the girls' continuing grades slip warrants drastic action: a team lockout, which makes the local TV news and because of official secrecy starts a rumors circuit.

The whole community is shocked to see Mary and half her Wildcats team meanly vandalized the school's gym. Simon and Ruthie feel guilty for not telling they overheard her planning 'something extreme', so they seek redemption in Catholic confession, a synagogue and a Buddhist temple. Matt feels guilty enough to move back in and resume his task as big brother, only to find that o longer requires his presence and return to his house-mates. Eric calls a marker on lawyer Bill Mays, he gets her in to a trial-avoiding parole office 'last chance' program.

Eric threatens Robbie with eviction because he thinks he's keeping secrets about Mary. The house is abuzz with secrets and preparations for an elaborate surprise party for Eric's birthday. Johnny drops Mercy on the Camdens' doorstep after Frankie abandons them. Mike trusts Lucy enough to look after his mother for a day, during which the woman surprises her, both by speaking and by what she says.

Everyone but Lucy is stuck home celebrating the twins' birthday on Valentine's Day; Lucy and Jeremy keep running into Lucy's ex-boyfriend.