Eric's stress level rises when he learns that Matt has lost his job at the hospital and is relying on his friends to find him new work. Simon is adding to Eric's tensions by pressuring him to let him get his learner's permit. At the same time, Lucy breaks off her engagement to Jeremy and just cries in her room and refuses to discuss what happened. Robbie, still longing for Mary, is moping around the house as she returns to New York to be with Wilson. Annie's behavior has Eric wondering what's going on with her and suspects she's pregnant.

Simon considers dating a sixteen-year-old pregnant Sally who he meets on the bus. Annie decides to accept Robbie's offer in renting the room over the Camden's garage that both Lucy and Matt were hoping to get. A carpenter pretends to fake an injury while working on the Camden's garage and tries to sue them. Mary gets more serious with being a firefighter, mother and wife to Wilson and Billy.

Eric tries to arrange a romantic evening with Annie, but Annie keeps turning down every attempt he throws at her. At the same time, Annie takes Eric by surprise with the news that she would like to quit college and to start teaching to help get her out of her depression. Meanwhile, Simon is at risk of being fired from his new job at the pizza parlor by his excessive tardiness and discovering that waiting tables takes more people skills than he's equipped to handle. Also, Robbie sets Lucy on a date with one of his friends while Matt is concerned about a woman who keeps showing up at the clinic a lot. Lastly, Mary performs terribly in fire fighting training distracted by her consuming relationship with Wilson.

Lucy and Robbie argue over who should tell Mary about their emerging relationship. Meanwhile, Matt worries that a young woman in his study group might be a victim of physical abuse at the hands of her belligerent boyfriend. Eric's sister Julie shows up at the Camden house with her toddler Erica and annoys Annie as she tries to prepare a lesson for her class. Simon meets up with Sasha and they both try to catch up on their personal lives.

Mary's sudden arrival has everyone in the family wondering what happened between her and Wilson. Only Mary knows and she's not telling. Her presence delights Annie, who goes out of her way to make her daughter comfortable, even offering her the converted garage apartment. But not everyone is happy to see her. Ruthie feels that Mary owes everyone an apology for the actions that led to her moving away.

St. Valentine's Day delivers a few surprises for the Camden family. A grounded Simon is asked out by a senior. Annie's attempt to surprise Eric with romantic Valentine's plans backfires and results in a big fight. Mary discovers Robbie's plans with Joy. Lucy and Mary learn that Jeremy and Wilson both have dates for Valentine's. Matt seeks his fathers help as he wants to settle down, which leads him to seek out old girlfriends as to why they're no longer together. Ruthie is hesitant to go to a party because her friend tricked her into asking out a boy she's already going out with.