`The Hills' follows the personal and professional lives of several young adults living in Los Angeles. Looking for some stability in her life, Kristin attempts to mend fences with Audrina and Heidi, but a rumour about her hard-partying lifestyle gets in the way. Also adding unrest is her relationship with Brody ... or lack of one, now that he has his eyes on someone he's never been able to snare - Audrina. And no one has changed more than Heidi, who looks for the approval of her mother and friends after undergoing numerous cosmetic surgeries. She also has to decide if her marriage to Spencer, now acting more distant than ever, is worth saving.
Series four kicks off with tension between Audrina and Lo pushing breaking point. Lauren throws them a birthday party, but a visit from Heidi's sister throws a spanner in the works. (S4, ep1)
Lauren runs into Spencer at Stephanie's birthday, and the birthday girl is torn between her brother and friend. Someone is fired at People's Revolution, and Whitney must step up. (S4, ep2)
Lauren realises that the chemistry she felt for Doug in high school is no longer there. Whitney's nervous about going to New York, and Spencer is cutting Stephanie out of his life. (S4, ep3)
A trip to Vegas breaks down when Audrina snubs Lauren. Brody brings up Stephanie's past, and the boys end up in jail. Heidi's sister wants to move in, but Spencer wants her out. (S4, ep4)
Lauren and Audrina fight to save their friendship, but is it too late? Spencer's had enough of Heidi's sister Holly and takes matters into his own hands. Brody and Doug get out of jail. (S4, ep5)
Heidi's sister Holly asks Lauren and Heidi to reconsider what happened to their friendship. Audrina and Justin's relationship is tested as she works a huge event for a record company. (S4, ep6)
Lauren leaves for a family vacation, and things in Los Angeles go awry. Meanwhile, Stephanie dates Doug behind Lauren's back, and Audrina gets friendly with Heidi. (S4, ep7)
The truth comes out about Stephanie's relationship with Lauren's ex, Doug, when they all meet up for the first time at his pool party. Heidi's mother surprises her in LA. (S4, ep8)
Lauren gets a letter of apology from Heidi and realises there's only one thing keeping them from being friends again. Audrina starts dating a new guy to make Justin jealous. (S4, ep9)
Audrina reconnects with an old flame, Cory, and finds herself juggling two guys. Spencer forces Heidi to kick her sister out of the apartment. (S4, ep10)
Lauren and Audrina travel to Cabo for Brody's birthday, but when Justin gets jealous of Audrina's new relationship, the party turns into a fight. (S4, ep11)
Lauren tries to make peace between Brody and Stephanie. Audrina wants to make things work with Corey, but Justin won't give up on her. (S4, ep12)
Audrina gets her own place, hoping Justin will move in with her. Heidi invites Spencer to a work event and gets caught having a little too much fun. (S4, ep13)
Whitney travels to New York expecting to reconnect with Alex, but a new boy named Jay steals her away. Heidi is miserable after being fired, and Spencer is making matters worse. (S4, ep14)
Whitney is called into Teen Vogue editor Lisa Love's office to receive some exciting news... she's being sent to Paris on Teen Vogue's tab... again! (S3, ep18)
Lauren lets Heidi's sister crash at her place. Justin asks Audrina to go away for a romantic weekend, and Heidi begs for her job back. (S4, ep15)
Lauren is enraged to learn that Audrina believed speculation that she and Justin were involved with each other. Heidi struggles balancing her relationships with Holly and Spencer. (S4, ep16)
Audrina tries to save her friendship with Lauren after accusing her of hooking up with Justin. Spencer and Stephanie visit their grandmother, who is fed up with their fighting. (S4, ep17)
Whitney gets offered a chance at her dream job in New York. Lauren grows nostalgic when she learns her parents are selling their house in Laguna Beach. (S4, ep18)
Spencer and Heidi ignore the concerns of their families and run away to Mexico. Whitney takes a chance at her dream job in New York and says goodbye to Lauren and L.A.! (S4, ep19)
When Lauren and Heidi have a run-in, they put their feud aside and remember why they used to be friends. Justin shocks Audrina by whisking her away to Palm Springs! Last in the series. (S4, ep20)