Girls Season 4 Episode 5 picks up with Hannah in her apartment freaking out about Adam and his new girlfriend.
At the end of Girls Season 4 Episode 4, Hannah makes the decision to leave Iowa and return to Brooklyn. Upon arrival she finds out that Adam has a new girlfriend named Mimi Rose Howard. Hannah flips out when she realizes what's happening and locks herself in her old room.
Adam calls Marnie, Jessa, and Shoshanna. Shoshanna shows up first and tries to help, but Hannah ultimately kicks her in the boobs and tells her to leave. Jessa arrives next and accidentally reveals that she's the one who set up Adam and Mimi Rose. Then Adam's sister and Laird show up and try to comfort Hannah. Ray comes the next morning and makes breakfast.
Everyone tries different modes of comforting Hannah, but nothing really works. Hannah obsesses over watching a lecture that Mimi gave. She wants to know about her and hate her, but I think is having trouble not admiring her a bit.
Finally Marnie shows up and tells Hannah what she doesn't want to hear "let Adam go." It is difficult, but good advice. Hannah packs up and she and Adam have a heartfelt goodbye. Then she heads to her new storage unit.