Nathan is working hard for not-so-nice Professor August Kellerman, but is finding it more difficult than he previously thought. During Brooke's hen night the girls have such a wild night that hangovers are their least concern. More worrying is the arrival of mother-in-law Sylvia, a stolen dog, it's owner's vandalized home, a frat and a missing engagement ring. Could bridal infidelity be added to that list, too?
The biggest day of Brooke Davis' life has arrived, her wedding day. Julian gets his parents to agree to a truce on their special day, but will they uphold their end? Brooke makes up with her mom, and when her dad fails to turn up, her mom walks her down the aisle. Nathan's advice of sincerity helps inspire Julian's 'best man' Jamie to make a brilliantly simple speech. Chase disagrees with Skills' absurd security-obsessed job description for them as ushers. He ends up making hotter use of the limousine.
As the girls plan a surprise baby shower for Haley, the guys participate in try-outs for Jamie's baseball team. Meanwhile, Brooke and Julian pursue adoption, while Mouth gets Millicent ready for her first day at work.
As Haley's due date approaches, she takes steps to ensure that all her friends and family will be ready when the time comes. Brooke and Julian also prepare to begin a family, while Chuck turns to Chase for help with a problem.
While Haley stays at home to take care of the new baby, Quinn organizes a concert at Tric. Meanwhile, Brooke gets an offer to return to Clothes Over Bros, and Nathan sets his sights on exposing Professor Kellerman.
Nathan gets Professor Kellerman to confirm the truth regarding the night of the accident. This leads to Nathan reevaluating the motivation behind his own father, Dan's actions. After coaching Jamie's first little league game, Nate, Julian & Clay confront Ian on the things they've discovered. Brooke has some life-altering news for Julian!
Haley and Brooke get ready to re-open Karen's Café as Brooke's pregnancy progresses. At her scan she discovers that she is expecting twins. Nathan and Clay set off on the road to scout new talent and it forces Nathan to finally go and see Dan. Chase leaves for the Air Force leaving behind two disappointed people - Chuck and Alex. Meanwhile, Mouth and Millie start their new morning show together but Millie is wooed away to start a new show with another co-anchor in Charlotte.