Aaron is wallowing in his sorrows after hearing that an ex-girlfriend is engaged to his old friend from MIT. Determined to pull him out of his funk, Ben and Fitz convince an unwilling Aaron to take a night out on the town to remind himself that he's not that nerdy kid anymore - he's an incredibly rich grown-up nerd who can get any woman he wants.
Riley's convinced that her roommate Sara doesn't want to be friends; every time she suggests plans, Sara says that she'll "check her schedule" and get back to her. Really, the two never hangout outside of a group setting. Later at the bar, Riley confides to the guys about her realization; every weekend, Sara dodges making plans.
When Sara arrives at the bar, the two diffuse the conflict, and Sara agrees to hangout that night. Riley claims that not all of her plans are strange; in fact, her pot dealer is having a retirement party that night. Clearly, Riley has a vey different definition of strange than Sara. Sara plays it cool and agrees to accompany Riley to the party that night.
The guys keep Aaron's celebration of independence rolling with a visit to an upscale bar. Aaron in particular takes a liking to their waitress, Kristen, and is very heartbroken when she leaves for a concert at the end of her shift. He makes Kristen write down the name of the guy at the table that she's most interested in on a napkin before leaving.
Worried that this game will do more harm than good, Ben intercepts the napkin and reads Aaron's name aloud, though we can see that Ben's name is written on it. But this ego boost for Aaron has a nasty side effect; he becomes transfixed on Kristen and determined to follow her to the concert to stage a casual run-in.
Meanwhile, a visibly anxious Sara arrives at the party with Riley. Sara nibbles on the snacks to curb her nervousness, only to learn that all of the food at the party is laced with weed. But it's too late to stop her now; Sara continues on a downward spiral so vicious, she ends up making out with a hobo.
Ben has led a very inebriated Aaron astray on his mission, putting them on a series of wrong trains to avoid an awkward confrontation at the concert. Unfortunately, the unthinkable happens; Kristen and her two friends actually show up on their train car.
Riley breaks the news to Sara about her hobo-encounter, and the two rush out to catch a train home. Unfortunately for Sara, no amount of orange soda will get rid of the hobo taste. Coming down from her high, Sara unloads on Riley; this is all her fault! Without Riley's influence, this would never have happened. Unsurprisingly, Sara's tantrum is interrupted by a bout of sickness.
The guys bring Kirsten and her friends back to Fitz and Aaron's place to seal the deal. The problem is, Kristen is fawning over Ben, and Aaron can't seem to understand why. When Aaron lashes out at Ben for hitting on his woman, Ben admits the truth; his name was written on the napkin, not Aaron's. Aaron refuses to believe it and confronts the girls, only to realize that Ben wasn't lying.
Later at home, curled up by the toilet, Sara apologizes to Riley for her behavior. The girls admit that they are both intimidated by the other; Sara admires how free-spirited Riley is, while Riley is jealous that Sara has her life together. They realize that despite their differences, they can still be great friends.
An upset Aaron won't come out of his room, that is, until Fitz suggests that they do "that thing where he decides whether Ben lives or dies." This leads to Ben on a pier with a cinderblock tied to his body. The decision is up to Aaron: does Ben deserve to have his life spared? Fitz reasons that if Aaron can't let go of his anger, Ben is better off dead. After serious consideration, Aaron decides to save him, but his decision comes too late; the pier breaks and Ben falls into the water with his cinderblock. Aaron dives in to save him, proving his worth as a true friend.