Robbie and Mary get to go to the movies on a double-date with his brother Rick and Lucy, but that unwilling couple ends up cheating on their partners, while Robbie has another secret. Simon and Nigel buy cigarettes illegally for a school project, yet Eric waits even while they ponder about smoking 'just one'. Matt is a wreck after Shana fails to call once, worse when she does too cheerfully, but his very despair attracts both girl neighbors his house-mate invited.

It is Valentine's Day, and the Camdens are celebrating the day of love with a special party in honor of the twins' first birthday. Eric and Annie fret over how to make it a memorable birthday, while the rest of the family learn different ways of exchanging love. After finally gaining her parents' trust, Mary is allowed to spend a romantic dinner with Robbie, only to learn he has ulterior motives. Meanwhile, Simon and Deena confess to their parents that they have given each other love bites. Also, Matt welcomes his ex-girlfriend Heather back into his life, threatening his relationship with Shana.