New roommates Lauren, Lo, and Audrina are thrilled to move into their new (expansive, $2 million) Hollywood Hills digs - and that means one thing and one thing alone: a memorable Hills housewarming party!

Lauren Conrad reveals that her high school sweetheart, Stephen Colletti, is in town and plans to attend. That makes Lo happy. Justin-Bobby attending at Audrina Patridge's request, however, does not.

Lauren Conrad and Stephen Colletti reunited on The Hills last night!

What happens next? That you'll have to read our episode guide to find out. Follow the link and catch up on all the drama from this episode of The Hills, fittingly entitled "A Date With the Past."