Set in the 1990s, the film opens with a tense flashback: battered Mark, Owen Campbell, stands before a mirror examining his wounds before he and his friend Jack, Charlie Heaton, slip away into the woods where a gunshot pierces the quiet. This confrontation is later examined from the vantage point of a police investigation, as detectives interrogate the core figures to uncover the truth behind the bond between Jack and Mark and the night that ended in tragedy.
Months earlier, Jack's single mother, Karen, John Scurti begins dating a man named Tom, Scott Cohen, who has a son Jack's age. Jack meets the son, Mark, Owen Campbell, and the two boys quickly form an inseparable connection. They also befriend a local girl named Sarah, Amandla Stenberg, who defends them when they are attacked by a group of thugs. The trio spends virtually all their time together, and while Mark does share a kiss with Sarah during a game of spin the bottle, their relationship remains primarily platonic at first.
Tom introduces his gun collection to the kids, and they spend time practicing in a nearby field. Before long, Karen suggests Tom and Mark move in with her and Jack, an arrangement Tom agrees to. The boys begin sharing a room and drift deeper into adolescence, experimenting with drugs while navigating the era’s turmoil, including the cultural fallout from Kurt Cobain’s suicide.
A turning point arrives when Jack reveals he has never kissed anyone, prompting Mark to offer to teach him how. The two share a kiss, and soon afterward they slip out to the woods with Tom’s firearms and kill a squirrel. That night, Jack witnesses Tom physically abusing Mark over a minor incident, a scene that foreshadows mounting tension as they skip multiple days of school. The strains between Tom and Karen intensify, especially when Karen discovers Tom’s plan for Jack to join the Marines without her knowledge, a plan that infuriates her. During a heated argument, Tom walks in on Jack, Mark, and Sarah watching pornography together, a moment that unleashes Tom’s violence and leads to Mark and Jack being moved out of Karen’s house. It devastates Jack, who has evident feelings for Mark.
Mark leaves the school, and Jack and Sarah grow closer after prom, though their relationship remains shallow in fanfare and deep in longing. The two eventually begin dating, only to realize that their connection with Mark remains a stronger, more complicated undercurrent. Mark and Jack later reconnect in private, and Mark hints at his own feelings for Jack as they share a passionate kiss.
In the interrogation room, the detective presses Jack to tell the truth about what happened at the skate park, while Jack’s accounts are cross-examined by others, including Sarah, who faces legal pressure to reveal what she witnessed. In the flashback sequence, Mark and Sarah reveal that they have started dating, and after Sarah walks away, Mark confesses to Jack that he cannot bear the potential consequences of their relationship. A desperate Jack pleads with him, and Mark falls and hits his head on a rock during a scuffle, though he is not critically injured. Later, alone in Mark’s room, Mark says he does not remember what happened, and the two men hold each other as Tom watches from a doorway.
Back in the interrogation room, Jack begins to break down under the detective’s aggressive questioning, the pressure mounting as authorities demand the truth about what occurred in the woods. It is eventually revealed that Mark is dead, a revelation that reframes every prior event in the investigation.
In the final flashback, Mark returns to Jack’s house with a battered face and shares a bottle of cough syrup with him. Mark rejects Jack’s tenderness and explains that he wishes he were a girl. In response, Jack tries to experiment with his mother's makeup and dress in a bid to reach Mark, but Mark remains distant. The two boys grab the father’s guns and wander back toward the woods, slipping into the familiar landscape where they once played. A single gunshot is heard as Jack runs from the woods, screaming for help. The interrogation ends with Jack asking for a lawyer, and the film leaves the ultimate fate ambiguous. It remains unclear whether Mark took his own life or if Jack fired the fatal shot. The ending lingers, inviting interpretation while staying true to the emotional core of the story.
