Will sees Dr. Sam to the airport for a heartbreaking goodbye as she departs for New York. On the escalator, she pleads with Will to move to New York with her. Will has a tough decision to make. He mulls his options and eventually decides that as much as he loves his life in Berkeley, he doesn't want to be apart from Dr. Sam. He's moving to New York City! Now he just has to break the news to Marcus.
Avoiding the toughest conversation of his life, Will decides to first inform his best friend, Andy, of his big decision. Andy is obviously not happy about the news, but he promises Will that he'll support him no matter what, because that's what best friends do.
Meanwhile, Will's old band, Sriracha, decides to play a reunion concert at a local club. A week of band rehearsals provides a good distraction for Will, who is still nervous about telling Fiona and Marcus that he's moving. He has a heart-to-heart with Fiona in the tree house, during which he informs her that he's leaving town. She's heartbroken, but she's more concerned about how Marcus will take the news.
Later that week, a man stops by Will's house in response to a subletting ad in the paper. Marcus confronts the man on the porch and discovers Will is moving away. He throws a temper tantrum and destroys part of the tree house, angrily screaming about how Will is leaving him just like his father did. This isn't how Will wanted it to go down at all.
Will and his band perform their reunion show, which Marcus declines to attend. For their last song, Will invites Fiona onstage to perform a heart-wrenching rendition of a One Direction song dedicated to Marcus. At home, Marcus begins to regret his angry response to Will's news. As a friend, he should be supportive, even if it means losing someone he loves dearly. He heads to the concert just in time to catch the end of Will and Fiona's performance, understanding what friendship really means.
After Will's big move, he calls Marcus to catch up on the events of the past week. He offers Marcus advice on girls and life, just like old times. When Fiona interrupts the call, Will tells Marcus about a secret chute in the tree house that Marcus can use to hide his barbecued rib bones from his mom. The two friends agree to chat again at the same time next week and, after hanging up, Will looks out at the New York City skyline and appreciates his wonderfully wacky life.
When Dr. Sam's apartment is condemned, Will invites her to move in, causing all reason to desert him. Adrianne Palicki guest stars.