Simon can't resists reading Matt's letters and thus discovers big brother is secretly married to Heather. Eric can't resist spying on both, and thus falls into a trap. Wilson won't say 'I love you' back to Mary, who refuses to understand he'll only say that again when even more serious then with Billie's late ma. Lucy's friend, new girl at school Laurie, is extremely timid due to her verbally brutal ma, but the scolding root sits deeper.

After Simon's school project volcano is carelessly ruined by brainless Ruthie, it's time for him to move to his own room. He's less happy with the isolated attic he's supposed to go to, but Matt agrees to move there and hand over his room, eager to 'move' to an out of state college anyway. Wilson calls Mary, but only to babysit Billy while he takes his date to her prom. Despite home advice, Mary performs miserably, yet Wilson returns early, having decided he only wants a girl who tells he family about Billy. Lucy desperately recruits enough big sibling support to get permission to go eat in town with two 'cool' sisters. Being driven in their car is forbidden, which turns out to be a life-saver, alas literally, leaving a guilt problem.

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.

The first weekend all seven siblings are home, Eric and Annie plan to extend their child-labor scheme to baby-sitting the noisy newborns. Matt starts his new job at the Dairy Shack, but can't stick it out with the owner's son as his hostile boss, but the evening holds one happy surprise for him. Mary slips away to meet Wilson and runs into Jordan, while Lucy does double chores. Happy is neglected and Ruthie feels neglected, and Eric ignores Simon's well-read parenting tips and steals his Dairy Shack order. Which family member restores heavenly peace to the household?

Robbie is told last, despite Camden's advice for her to be open, that Mary has bumped into her ex Wilson, who does a course in Buffalo, and agreed to a dinner at his place. Robbie is doubly vexed as he immediately calls her after meeting a lookalike, Marie, also a basketball player, whom he asked over to get hold of her study notes. Matt meets and dates Cheryl before he realizes she's Robbie's ex. Mary also bumps into Lucy's Jeremy.