A distraught Peter learns that his alcoholic and mean-spirited father who abandoned his family three years ago, has changed his ways and wants to be part of Peter's life again. In the wake of this monumental news, Chandler must decide how this will impact his relationship with Paris and Peter. Meanwhile, Ruthie feels that Peter is pushing her away during this chaotic time and Reverend Camden finds a philanthropic way for the community and his family to embrace Vic.

On a temporary leave from military duty in Iraq, Martin's father pays the Camdens a visit to help his son decide whether to forgo college for a career in professional baseball. However, the visit turns sour when Martin catches his father kissing Roxanne. Meanwhile, Chandler and Paris reevaluate their relationship in the wake of her ex-husband's return, and Roxanne comes to blows with Martin's aunt over their differing views on the war in Iraq. Lastly, Vic tries to join the Marines and talks to a supervisor over the matter.

Matt returns to Glenoak to celebrate a special anniversary with Ruthie and tries desperately to avoid seeing the rest of the family. However, when Lucy discovers the secret, she, Eric and Annie go crazy trying to figure out why he's in town. Meanwhile, Martin shares something special with Cecilia. Also, Annie lets it slip to Nurse Kelly that Matt and Sarah are married. Lastly, Vic invites Paris to spend a special evening with him, but she doesn't want to go because she thinks he might propose.

The Camdens, especially Lucy and Ruthie, grow concerned that an unusually joyful Annie isn't dealing with her true emotions following the death of her father Charles, but the happiness proves to be infectious as it soon spreads through the family and all over town. Meanwhile, Eric tries to convince an unhappy Chandler that he should consider adoption. At the same time Chandler is approached by a mysterious young girl who gives him a cryptic message before she disappears.

Prospective homeowners Lucy and Kevin are ready for a fight to the finish when they learn that Chandler and his soon-to-be-adopted son Jeffrey are their rivals in a bidding war on a house. However, the conflict sparks an idea with Eric and Annie who decide to use their savings to buy their house from the church. Meanwhile, Ruthie is upset with Martin because she thinks he will get the garage apartment instead of her when Lucy and Kevin move out, and Peter suspects that his dad might be having an affair.

Lucy and Kevin celebrate their one-year wedding anniversary and contemplate whether they're ready to start a family, but things don't go off smoothly as Lucy refuses to drink champagne with Kevin during their anniversary dinner. Cecilia and Martin realize that their relationship may face a rocky future if Cecilia goes away to college. Chandler's foster son asks him to rid their house of all alcoholic beverages.

Peter lies to Ruthie about his plans for the evening when she asks him to help her baby-sit the twins. With that, Peter goes missing, but concern turns to disappointment when Eric and Vic find him drinking alcohol with his friends at the park.

The Camden chaos continues with Matt, who is trying to salvage his marriage, questioning whether he still has feelings for his ex-girlfriend Heather; Simon's return to Glenoak creates conflicted feelings for his ex-girlfriend Cecilia, who is torn between her feelings for Simon and her current boyfriend Martin; Ruthie's foreign exchange student friend Maria, appears to be making the moves on Ruthie's boyfriend Peter; and grandparents-to-be Eric and Annie hop a plane for New York, despite Mary's repeated pleas for her family to stay away.

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.

Annie and Ruthie spend the day together to unwind, while Lucy's world becomes complicated by both professional and personal news, and Eric unintentionally shakes up things between Rose and Simon.