While making her way home, Lindsey, a student at Hawthorne College, becomes the victim of a brutal attack by a trio of masked figures. As the rest of the college community prepares for the festive holiday break, Riley Stone, portrayed by Imogen Poots, battles her own haunting past stemming from an unreported rape committed by Brian Huntley, the president of the DKO fraternity, which few believed. As she navigates this trauma, her supportive sorority sisters—Kris (played by Aleyse Shannon), Marty (Lily Donoghue), Jesse (Brittany O'Grady), and Helena (Madeleine Adams)—gear up for a talent show that features a dance routine choreographed by Riley herself. In an emotional gesture, Riley gives Helena her cherished lucky comb.
Meanwhile, Kris has riled the DKO fraternity members and Professor Gelson (Cary Elwes) by advocating for a petition that calls for the removal of the bust of Caleb Hawthorne, the college’s founder known for his misogynistic views, from the main building. Another petition challenges Gelson's outdated curriculum that dismisses literature authored by women. During a shift at the coffee shop, Riley receives unsettling news about Brian's return to oversee the talent show and meets Landon (Caleb Eberhardt), a charming boy who shows interest in her.
As the sisters attend the DKO event, Riley stumbles upon a peculiar ritual involving the fraternity’s new pledges while also witnessing a disturbing incident where Helena is nearly assaulted. Taking action, Riley ensures Helena is safely sent home. Seizing her chance, Riley performs a powerful song with her sisters at the talent show, calling out the prevailing rape culture and declaring that "Brian did rape Riley." Their performance lifts spirits, allowing Riley to bond further with Landon. However, the dark events escalate when Helena falls victim to Lindsey's attacker.
The following day brings a series of ominous direct messages from an account linked to Caleb Hawthorne, eerily reminiscent of the messages received by Lindsey before her death. As the girls grapple with these threats, the horror intensifies with the murder of sorority sister Fran (Nathalie Morris) by the same masked assailant. With Helena's whereabouts unclear, Riley alerts the unhelpful campus security, who dismiss her concerns, assuming Helena has simply gone AWOL with a boyfriend.
Tensions flare between Marty and her boyfriend Nate (Simon Mead), culminating in a heated argument that leads to Nate's exiting the house, only for him to later fall victim to the killer. The mounting chaos spirals as Jesse is found lifeless in the attic, and the remaining sisters, Riley, Kris, and Marty, fend off a bow-wielding attacker who injures Marty before the girls manage to lock themselves in a room for safety.
Desperate, Riley ventures out for her phone while Kris goes to check on Jesse, only to discover her terrible fate. In a turn of events, Nate returns attempting to apologize, but meets a gruesome demise. Riley, empowered by survival instincts, manages to defeat the masked attacker before she and Kris find themselves facing two more assailants. Tragically, Marty succumbs to her injuries, sacrificing herself to ensure Riley and Kris escape to safety in Nate's car.
As they flee, Riley theorizes a connection between the killings and Hawthorne's sinister legacy of black magic associated with the bust. Disagreeing passionately, Kris insists they head to the police, but Riley, fueled by anger, decides to confront the DKO fraternity directly, recruiting Landon's help to infiltrate the house. Meanwhile, Kris discovers that jersey-bound pledges have also targeted Lindsey's sorority sisters, prompting her to spring to their defense.
Inside the DKO house, chaos erupts when Landon is coerced into pledging, while Riley encounters alarming evidence of Hawthorne’s influence as the bust continues to ooze the black goo. In a shocking revelation, she finds Helena alive but held captive. Just as Riley attempts a rescue, she is overpowered. Awakening to face off against Professor Gelson, Brian, and the DKO brothers, Riley learns of a dark plot involving an ancient spell using the black goo, which allows the spirit of Caleb Hawthorne to possess the fraternity's pledges and compel them to harm rebellious women.
Betrayal strikes as Helena reveals her complicity with the fraternity, only to be murdered by a pledge as a display of dominance. With her fate uncertain, Riley is demanded to submit to Brian, but steadfast in her resolve, she plots revenge. At a crucial moment, Kris leads the remaining sorority sisters into the fray, and a fierce battle ensues. Ultimately, Riley defeats Brian and shatters the Hawthorne bust, liberating Landon from his trance.
With Kris igniting Gelson in a blaze, the group escapes and locks the fraternity brothers inside, leaving the house to meet its fiery end. As they witness the destruction, Riley is transformed by her experiences, embracing a new-found strength.
In a chilling post-credits scene, a cat beloved to the MKE sisters is seen licking the remnants of the malevolent black goo, hinting that the darkness may still linger.
