A group of high school students, Alice, Scottie, Emily, and Louis, are assigned detention over the summer to clean up their vandalized school. Each carries personal traumas and dark secrets that have isolated them from their peers. As they begin their work, they quickly find themselves trapped inside the school by a group of masked intruders who appear intent on inflicting terror. The students' fears materialize into nightmarish scenarios within the confines of the school's halls and classrooms.

As the tension escalates, the students must navigate both physical and psychological threats while wrestling with their own inner demons. The masked figures seem to have an intimate knowledge of each student's fear, manipulating their environment to bring those fears to life. The line between reality and delusion blurs as past traumas resurface, forcing the students to confront their darkest memories. Struggling to find a way out, they must come together despite their differences and uncover the truth behind their shared nightmare.