“There’s Someone Inside Your House” starts out with obnoxious high school football player Jackson Pace (Markian Tarasiuk) heading home to take a nap before a big game. When he wakes up, he fearfully realizes that there is indeed someone inside his house, plastering the joint with incriminating photos of him beating up a gay teammate during a hazing session. The intruder isn’t just intent on exposing his shameful behavior, however. Wearing a 3D-printed mask of Jackson’s face, they stab him to death before sending footage to everyone in the school.
The next day, Jackson’s fellow jocks are grieving his brutal murder. Less so are a group of misfits who form their own snarky little circle: Makani (Sydney Park), a seemingly normal girl who moved from Hawaii to live with her grandma; Alex (Asjha Cooper), the group’s “resident b****;” Zach (Dale Whibley), a pot-smoking rich kid who hates his wealthy dad; Darby (Jesse LaTourette), a non-gender-conforming student who dreams of working for NASA; and Rodrigo (Diego Josef), who hides his painkiller addiction from his friends. Lurking around the outside is Ollie (Théodore Pellerin), a loner who everyone immediately marks as the prime suspect.
It’s not long before the killer chalks up their next victim: Katie (Sarah Dugdale), the goody-two-shoes school president who the murderer slices and dices while revealing her involvement on a white supremacist podcast. The killer’s M.O. is clear: They prey on people with secrets that could see them canceled if the murderer wasn’t permanently canceling them with a big knife instead.
As the police impose a curfew, Zach throws a big party for everyone to share their secrets, theoretically denying any hold the killer has on them. But Makani is still wary of revealing why she left Hawaii for a small town in Nebraska …