After Lucas and Keith learn that Dan had a heart attack and is still in the hospital, they decide it is best for them to return to Tree Hill. When Deb learns about Haley and Nathan's marriage, she grows hostile. Meanwhile, angry that Lucas left Tree Hill without saying goodbye, Peyton and Brooke try to mend their friendship.

With the assistance of Peyton and Brooke, Lucas throws Nathan and Haley a wedding reception. Although Haley's parents support Nathan and Haley's marriage, Deb has a difficult time accepting it. Meanwhile, Dan's recent heart attack causes him to try and mend his relationships with Deb and Lucas.

Haley, Quinn and Taylor receive a surprise visit from their mom Lydia who tells them that she has incurable pancreatic cancer and that she is not seeking any further treatment. Quinn takes the news very hard but Clay is there to support her. Meanwhile, Alex sets her sights on Alexander as Brooke and Julian try to get their old relationship back on track, and Millicent finds herself struggling with temptation.

Haley and Quinn refuse to accept that their mom Lydia will not fight her pancreatic cancer and after some convincing manages to persuade her mother to get a second opinion with Nathan's doctor but the results don't bring any change. Because she told Jamie that she won't be alive for Christmas he organizes for her to have Christmas now with the family. Meanwhile, Brooke and Julian's relationship moves up a notch but comes crashing down spectacularly when Brooke finds Alex in his bed but is it what it seems? Elsewhere, Grubbs puts Miranda through hoops before he allows her to produce his album with her and Owen Morello comes back into Millie's life much to Mouth's displeasure.

In getting back at Julian for sleeping with Alex, Brooke messes with the costumes for the shoot and generally does her best to wound Julian but it takes comments from Alex to get her thrown off the set after she punches Alex in the face. Only later does she discover that it was Alexander that Alex slept with as she switched rooms with Julian. She tells Victoria who is furious and it later transpires that her mystery lover is Alexander. Meanwhile, Lydia takes ill from her cancer and is hospitalized and reaches out to the daughter Taylor but it is Quinn who manages to get her to come before she dies. Elsewhere, Clay tells Katie he won't be representing her but it doesn't put off Katie and she finds out that he was married to Sara so she transforms herself to look like her. Lauren and Mouth nearly get it together only for Skills to come back to Tree Hill.