Dennis, a young gay man living in Portland, Oregon, meets a man named Rocky at a diner. The two hit it off and have sex. Over the next few days, Rocky ignores Dennis's attempts to communicate, leading Dennis to visit Rocky's apartment in an attempt to speak with him. Unobserved, he sees Rocky with another man and follows them in his car. He eventually approaches them on the street and confronts Rocky for rejecting him. As Rocky begins to reply, he steps into the street and is fatally struck by a car.
Rocky's twin, Roman, grieves the death of his brother. He joins a support group for twinless twins and quickly makes the acquaintance of fellow attendee Dennis, who wound up in the support group by following Roman from Rocky's funeral. Dennis lies about having had a twin to get close to Roman, and the two become close friends. Dennis introduces Roman to his colleague Marcie; the two become a couple, leading Dennis to become jealous. Eventually, Marcie begins to notice inconsistencies in Dennis's claims about his family life. When she uncovers the truth, she insists that Dennis disclose his lies to Roman.
While sharing a hotel room with Roman, a drunk Dennis offers him a foot massage, which Roman accepts. Overcome with transferred lust for Rocky, Dennis begins sucking Roman's toes. When Roman declines his advances, Dennis confesses his deception. An angry Roman punches Dennis repeatedly and leaves. Roman and Dennis become socially isolated after falling out, while Roman and Marcie continue their relationship.
Some time later, Dennis and Roman meet at a diner, where they discuss Rocky and their friendship. In unison, they ask a waitress for a to-go box, an idiosyncrasy once shared by Roman and Rocky.
When the film was made available to festival viewers who opted to view the film remotely online during Sundance, clips and GIFs from the film showing O'Brien's character having sex were leaked online and shared across social media platforms. The clips were later taken down after copyright infringement claims were filed, and the film itself was later removed from the Sundance online platform.
On the review aggregator website Rotten Tomatoes, 97% of 150 critics' reviews are positive, with an average rating of 8/10.The website's consensus reads: "James Sweeney's sophomore outing reveals a twisty, grief-ridden journey of the unexpected– buoyed by a perfectly sensitive Dylan O'Brien." Metacritic, which uses a weighted average, assigned the film a score of 79 out of 100, based on 28 critics, indicating "generally favorable" reviews. Audiences polled by CinemaScore gave the film an average grade of A on an A+ to F scale.
Benjamin Lee of The Guardian termed it a "dark, inventive comedy", adding that the "smart and highly unusual film earns its boundary-pushing because he never loses sight of the inescapable, human sadness at its core". The Hollywood Reporter's Lovia Gyarkye commended O'Brien's dual performances and was appreciative of Sweeney's craft in "shifting between dry humor, gutting devastation and emotional poignancy".
Commenting on Sweeney's direction, Peter Debruge of Variety wrote, "On just his second film, the gifted young helmer demonstrates a sophisticated sense of framing, pace and exquisitely uncomfortable dramatic tension".
