Two roommates, Allie Clare McNulty and Harper Bridey Elliott, are at a rooftop gathering for their twin musician friends when they meet two guys, Russ Jeffrey Scaperrotta and Sam Griffin Newman. After the boys announce they will spend the day at Fort Tilden, the pair plan to meet them and bring them ecstasy.
The following day, with ferries closed, the girls decide to bike to Fort Tilden and borrow a bike from their upstairs neighbor, Ebb Neil Casey. They pick up the drugs from Harper's friend Benji Peter Vack. As they ride through Brooklyn, Harper stops at a cheap clothing store, and Allie realizes she forgot a bike lock. Harper suggests wrapping the chain around the bikes, but a boy in line steals Allie’s bike. Hesitant to confront him, they watch as he rides away, and Harper urges Allie to leave Ebb’s bike behind, eventually concealing it in trash to deter theft.
They call a cab driver who offers to take them to Fort Tilden for a hundred dollars. In the car, Allie grows frustrated because her Peace Corps contact Cabiria keeps texting for information. Harper makes small talk with the driver, who is from Calcutta and mentions having been there, but after Harper mentions her father’s job they are dumped from the car by the cabbie, who tells her her father “is a criminal and a bully.”
The girls walk the rest of the way to Fort Tilden, only to realize they are actually at Jacob Riis Park. While wandering, they rescue three abandoned kittens, then, after a text from Cabiria about how she’s enjoying the beach, discover Harper has posted a photo of Allie in her bathing suit on Instagram. Frustrated, they abandon the kittens in a trash can, reasoning they left them better than they found them.
As they continue their search, they learn the boys are at Jacob Riis Park. The girls finally return there and, on their way, pass Fort Tilden. At Jacob Riis Park they see the boys with two topless girls. Reluctantly, Harper and Allie remove their own tops, and as the sun begins to dip, Harper pulls Russ into the water in an attempt to have sex. Through conversation, Allie learns that the four young men are in high school, a fact she communicates to Harper: the kids are in high school.
Afterward, Allie and Harper call a cab home. On the ride, Harper dials 911 to report the kittens, but the operator tells her to retrieve them before rain washes them away; Harper ends the call.
Back home, Allie goes to see Ebb and tells him she abandoned his bike and may not pursue the Peace Corps after all. Returning to their apartment, she finds Harper talking with her father, who she asks about how he figured life out at her age. The night ends with the two friends sharing toast and listening to the latest song from their twin musician friends.
