There is cause for alarm when the Camden's disapprove of Simon's new group of friends, one of whom insults Annie and Lucy with his chauvinistic remarks. Norton, the kid that Simon befriends is a fan of violent rap whose negative attitude towards women seems to be influenced by misogynist lyrics. At the same time, Eric and Annie confront Simon about his newfound interest in rap music and somewhat misogynist attitude towards women. Heather gets back in touch with Matt, but Matt is unsure of her intentions. He then finds out that she is dating someone else AGAIN!

Despite the disapproval from the rest of the family and his own hesitations, Eric takes in Mary's ex-boyfriend Robbie Palmer (Adam LaVorgna) to live with the Camden's for the night after learning that he's homeless. Matt also shows up unexpectedly after being kicked out of his apartment by John, who needs quality time with his girlfriend. Meanwhile, Mary calls home again and hears Robbie's voice on the other end and assumes he's dating Lucy now. Also, John proposes to his girlfriend Priscilla in front of Matt.

A month has passed since Eric invited Mary's ex-boyfriend to stay with the Camden's until he got on his feet. Robbie happily continues to act as a member of the household--- and it's driving Annie crazy. Robbie is Eric's latest 'project', Ruthie's new best friend, recipient of Simon's financial advice, and according to Mary, Lucy's boyfriend. He's even cooking and folding laundry (the wrong way!). Frustrated and emotionally strained, Annie starts to think nobody needs a mother anymore. Also, Matt also feels unneeded from the family due to Robbie and pays an unexpected visit to Heather and her new boyfriend.

After their lackluster attempt at kissing, Mike (guest-star Jeremy Lelliot) and Lucy agree to be friends and to fix each other up on dates--- but the plan bothers Lucy more than she anticipated. Meanwhile, Matt's in a huff over John and Robbie's newfound friendship and feels slighted by the family. Eric also continues to feel alienated from his family when they keep going to Annie for advice. Also, Annie feels slighted when Ruthie plays an un-funny joke when the twins recognize her as their ""mama"".

Mary's feelings for Robbie resurface when she inadvertently finds out he has a secret date for Valentine's Day, and the whole family schemes to uncover the mystery woman. Meanwhile, with the exception of Lucy who has a date with Jeremy, the other Camden kids feel deflated when their Valentine's plans fall through and they end up stuck at home celebrating Sam and David's second birthday. Lucy and Jeremy's first date does not go as expected as they both keep on running into Lucy's ex-boyfriends. Although all's well that ends well by the end of the episode for everyone.

Mary returns home back to Glenoak for the summer to spend some time with her family, but fears about being together again with Robbie. Eric and Annie are recipients of what may or may not be advances from unmarried acquaintances. Simon and Deena see that they still have feelings for each other, even though she has a boyfriend. Matt agonizes over telling his family about his new relationship with Cheryl, but soon decides to tell them all. Lastly, Lucy surprises herself and others when making a proposal to Jeremy and the possibility of going to college in New York with Jeremy. Although plans change when Mary, feeling rejected by Robbie, makes a shocking declaration.

Mary tries to right a wrong by explaining to Lucy that she never had adult relations with her sister's fiance. The only problem left is trying to convince Lucy. Wilson unexpectedly drops by the Camden home from New York to see if he and Mary are really over by finding out her answer. James talks to Eric about him attempting to have an affair with Annie as Serena comes clean with Annie about her trying to have an affair with Eric. Robbie and Wilson set aside their differences so that they can talk about Mary. Matt learns a few things when it comes to Cheryl's honesty when she doesn't tell her friends that she's dating him.