The episode, which is currently filming in Vancouver, will also feature a performance by Sarah McLachlan of her new single 'Forgiveness'.
"The crossover episode of Life Unexpected brings One Tree Hill characters Haley and Mia to a music festival, sponsored by a Portland radio station and hosted by Ryan (Kerr Smith)," read a press release.
"At the concert, Haley and Cate (Shiri Appleby) meet and discover that they have incredibly similar pasts. It turns out that both women were somewhat nerdy, overachieving teenagers who got pregnant in high school by athletes named Nate (or Nathan). And when a secret of Cate's gets outed, Cate turns to Haley for advice."
The crossover will air on October 12 at 9/8c on The CW.