The film begins with Bailey challenging her college roommate, Harper, to take a stand and break free from her abusive boyfriend, Sam. Joined by their other roommates, Angela and Mallory, they head to a Halloween party, where they meet the charming athlete Nathan and his boisterous friend, Evan. The group embarks on an adventure to an extreme haunted house, where sinister figures donning Clown, Ghost, Witch, Vampire, Devil, and Zombie masks create a frightful atmosphere. As they explore the attraction, they stumble upon a shocking scene: the Witch torturing a helpless woman, making the chilling experience feel all too real.
Soon, tensions rise when the group splits at a fork in the maze. While Evan, Mallory, and Harper take one path, Bailey, Nathan, and Angela venture down another route which leads to a harrowing test of courage that leaves Bailey injured and without the heirloom ring she had borrowed from Harper. As Evan and Harper navigate the maze, they lose track of Mallory and are forced to press on, briefly crossing paths with a chainsaw-wielding Zombie.
Reuniting with Bailey, Nathan, and Angela proves challenging as they find themselves locked in a room, helplessly witnessing the Witch seemingly eliminate Mallory from the game. In an act of desperation, Nathan decides to forge ahead alone, encountering the masked Ghost, who introduces himself as Mitch. With a cryptic promise to help, Mitch insists that everything is part of the performance and no one was meant to get hurt. Unfortunately, their hopes are dashed when they discover that the emergency exit leads to a solid brick wall, trapping them further.
In a harrowing turn of events, the group decides to retreat through a narrow tunnel, but as Evan goes through, Mitch boards it up, leaving Nathan stranded. Just then, the Devil appears where the girls are hiding and horrifyingly kills Angela with his pitchfork. In the frantic escape, Bailey narrowly evades the Devil, while Harper, driven by fear and memories of her abusive father, confronts the masked menace, thinking he might actually be Sam.
The situation spirals further into madness. The Clown uses Harper's phone to taunt Sam, intensifying the chaos. As Mitch reveals his true self to Evan and kills him, Nathan finds Bailey's ring and manages to text Sam their location through Harper's phone before chaos ensues again.
Harper, caught in a brutal game of life and death, navigates various traps designed to torment her. In a critical moment of growth, she draws strength from memories of her past, overcoming her fears to battle back against the Devil. Their brutal confrontation culminates with Harper cleverly manipulating the situation to her advantage, resulting in the Devil’s demise.
Meanwhile, when Sam arrives at the haunted house, he triggers a deadly trap that seals his fate in a gruesome manner at the Clown's hands. As Harvey and Nathan fight for survival, they collectively confront the remaining masked killers, including an unassuming Vampire who mistakenly thought he was part of harmless entertainment. In an intense showdown, they defeat the Witch and manage to escape the nightmarish haunt. However, the harrowing saga does not end there—time passes, and in a climactic moment, the Clown tries to take revenge by breaking into Harper's parents' house, only to find himself caught in a trap set by Harper, who is armed and ready to end the horror once and for all.
