When new mom Lucy welcomes guests over to see the baby, Annie immediately becomes concerned, believing that Lucy doesn't fully understand the health risks of exposing a newborn to strangers. Lucy's determination to show everyone that she has parenting under control leaves Kevin to question his role as a father, especially when they're alone. Also, struggling new parents Kevin and Lucy move back into the Camden home, while Martin moves into the garage apartment.

Eric is worried that he and Annie are doing too much in helping Kevin and Lucy adjusting to parenthood as they're taking on more than they should as grandparents. Meanwhile, Martin's classmate Zoe (guest-star Katie Cassidy) intentionally falls asleep on the couch of his apartment so that she can tell everyone at school that they slept together. When Ruthie finds out about Martin's overnight guest she sees it as the perfect opportunity to blackmail him into getting her a date with her crush, Vincent (guest-star Thomas Dekker).

The streets of Glenoak are alive with the sound of music as the Camden family breaks into song for a very special Valentine's Day musical episode. Classic songs (""Love Is Sweeping the Country,"" ""You Were Meant For Me,"" ""Nice Work If You Can Get It,"" among others) are performed by the Camdens.

Simon is enjoying having his new girlfriend, Anna, who he just met the day before over at his apartment for Valentine's Day. They both agree to go to Glen Oak, but he decides to keep her away from his family for the time being. Annie displays her unhappiness to Simon in song (along with the rest of passerbys) over his constant dating habits at the promenade as the chorus is going on. Anna overhears this and begins to question Simon and his dating habits as well. Vincent confronts an unhappy Ruthie on the high school bleachers as she's not in the Valentine's Day mood and is upset over watching Martin practice with his team and Zoe blowing kisses at him.

Also, Lucy and Kevin dance to ""You Were Meant

After being taunted for wearing second-hand clothes at ""Second Hand Rose"" by Vincent's (guest-star Thomas Dekker) new girlfriend, Margot (guest-star Ashley Benson), a distraught Ruthie runs into the bathroom and finds Martin's girlfriend, Zoe (guest-star Katie Cassidy), recovering from a fainting spell as two girls try to help her. Zoe confides that her family doesn't have enough money for food and makes Ruthie promise not to tell anyone.

However, when Martin breaks up with Zoe because he doesn't like her conceited attitude, Zoe thinks Ruthie has betrayed her confidence. Meanwhile, Kevin unsuccessfully tries to create some alone time with Lucy, but is frustrated with Lucy's obsession over Savannah. Also, Eric and Annie suspect that Sam and David are feigning being sick so they can stay up late and eat sweets. Lastly, Sam is jealous of the attention being given to an ill David.

An extremely nervous Simon comes home to Glenoak to await the results of his STD test. Eric counsels a woman (guest-star Erika Alexander) who is caring for her two daughters (guest-stars Bree' Anna Banks and Brandi Vanice) with sickle cell anemia and whose absentee father (guest-star Victor Love) is hoping to take them back with him to Memphis for treatment at St. Jude Children's Research Hospital.

Meanwhile, Ruthie's ex-boyfriend, Peter (guest-star Scotty Leavenworth), pays her a surprise visit, which creates problems with her current boyfriend, Vincent (guest-star Thomas Dekker). Lucy and Kevin disagree over who should care for Savannah when Lucy returns to work. Lastly, Martin misses an important call from his father in Iraq while sneaking out of the house to be with his girlfriend.