Charlie, a high school student navigating her parents’ breakup, is tasked with welcoming and looking after a new student named Sarah. Sarah is described as a white girl who has recently moved from Nigeria, where her mother works for a charity, to live with her aunt. The two girls quickly become inseparable, forming a close bond that feels like a lifeline during a turbulent time in Charlie’s life.
On All Saints’ Day, Sarah explains that her mother cannot visit and that she’ll be alone, so Charlie invites her to spend time with her mother and the people she knows for the holiday. The plan seems to be a simple gesture of friendship and support, but the dynamics between them start to shift in subtle but significant ways.
Their relationship takes a troubling turn during a vacation. When Charlie introduces Sarah as a classmate rather than a friend, Sarah’s attitude hardens and then softens, alternating between warmth and coldness. Upon returning to school, Charlie tries to approach Sarah with genuine concern, asking what is wrong, but Sarah’s mood remains mercurial. The tension is palpable as Charlie welcomes Sarah back with a friendly hug, even as a chill runs through the friendship.
Charlie’s suspicions grow as Sarah’s stories about her mother don’t quite add up. In front of their circle of friends, Charlie points out inconsistencies in Sarah’s accounts, attempting to uncover the truth. Sarah responds with a chilling threat: she could tell Charlie’s friends about her abusive father, something Charlie had confided to Sarah in private. Determined to uncover the truth, Charlie follows Sarah to her home and discovers that Sarah lives in a rough neighborhood with an alcoholic mother, a revelation that deepens the sense of unease surrounding her new friend.
A New Year’s party becomes a flashpoint. Charlie reveals that she has seen Sarah’s mother and asserts that Sarah isn’t truly as mean as she pretends. In response, Sarah threatens to kill Charlie if she ever tells anyone what she knows. The two drift further apart as the tension escalates. Later, Charlie overhears Sarah telling another friend that Charlie never lost her virginity with her ex Lucas because she cried too much, a cruel insinuation that prompts Charlie to threaten exposing Sarah’s mother. In retaliation, Sarah vandalizes the school with a cruel message: “Charlie is a whore.” While Charlie’s friends try to rally around her, she does not intervene to stop Sarah’s ongoing abuse.
The situation worsens when Sarah appears at Charlie’s house, crying because her mother hit her and she has nowhere else to go. Charlie forgives her, insisting that Sarah is only upset when they’re apart, and she welcomes her back into the orbit of their friendship.
The next day at school, the fragile balance shatters again. Sarah ignores Charlie and even passes along a necklace—one that had been given to Charlie’s mother—to another girl. In a moment of anger, Charlie lashes out and attacks the girl involved.
As summer ends, Sarah visits Charlie’s home to collect her things. They sit on Charlie’s bed, and Sarah taunts her, accusing Charlie of being an abuser who is playing the part of a victim. Sarah reveals plans to move to Paris with another friend to attend college, while Charlie will remain in their small town. Charlie’s restraint shatters: she pushes Sarah, Sarah’s head hits a drawer, and she falls back onto the bed, laughing. Overwhelmed by rage and despair, Charlie suffocates Sarah with a pillow.
When Charlie’s mother returns home, Charlie breaks down, crying and apologizing, and blurts out that Sarah is upstairs. A panic attack follows as her mother ascends the stairs and screams upon discovering Sarah’s body. Charlie struggles to control her breathing and then meets the camera with a blank, frightened gaze as the scene fades to black.
