High school student Jane Shipley is striving to mend her splintering relationship with her childhood best friend Merritt, and fit in with Merritt’s rebellious group of friends. When Jane's math teacher oversteps his bounds after class, an apathetic administration forces Jane and Merritt to take matters into their own hands. Merritt manipulates the situation against Jane's wishes, driving their relationship into further turmoil. Still seeking her approval, Jane joins Merritt and her clique as they break into the school that Friday night to party and play a prank. The group soon discovers they’re not alone: someone has locked them inside and is hunting them down one by one. To survive the night, Jane must find the strength to escape the locked doors and toxic relationships trapping her within Allendale Preparatory High School.