‘There’s Someone Inside Your House’ Ending Explained: Who Is the Killer?

Warning: This article contains major There’s Someone Inside Your House spoilers. That is why you clicked on it, isn’t it?

There’s Someone Inside Your House, a new slasher horror movie that is now streaming on Netflix, indulges in several classic tropes. First, as an ensemble coming-of-age high school movie, you’ve got the “secretly a softie” bad boy character, played with style by Théodore Pellerin. Then you’ve got the whodunnit murder-mystery aspect, complete with clues and red herring. And, perhaps less intentionally, you’ve got the convoluted horror movie ending that makes you go, “Huh?”

Based on the 2017 book by Stephanie Perkins of the same name, There’s Someone Inside Your House was adapted for the screen by Henry Gayden and directed by Patrick Brice. While the cast of characters is strong, and the setup is fun, the plot ultimately leaves something to be desired. Luckily, for those who got lost in the weeds in this story, Decider is here to help.

Read on for a plot summary of There’s Someone Inside Your House, including the There’s Someone Inside Your House ending explained.

THERE’S SOMEONE INSIDE YOUR HOUSE PLOT SUMMARY:

Makani Young (Sydney Park) is a high school senior who recently transferred to a school in the middle of nowhere, Nebraska. But it’s not as boring as you might think: A serial killer is on the loose who is killing students—while wearing a 3D-printed mask of their face—after exposing their deepest, darkest secrets. A popular football bro is murdered in his home, and a video is released of him beating up a gay kid on the football team. A popular Christian girl is murdered in a church, and audio is released of her spouting white supremacy on a podcast.

Makani has a few secrets of her own. Number one, she had a summer fling with the town’s resident bad boy weirdo, Ollie (Théodore Pellerin), whom everyone suspects to be the killer. Number two, Makani Young is not her real name. We don’t know exactly what happened to cause Makani to change her name and transfer schools, but it is something bad enough that Makani fears she’s next on the killer’s list. But her friends have their own baggage—like her friend Zach (Dale Whibley), the son of a wealthy farm owner. Everyone hates Zach’s dad, the owner of Sanford Farms, for squeezing out the businesses in town. Zach says he hates his dad too and laughs along with the jokes everyone makes.

As it turns out, Makani’s friend Rodrigo (Diego Josef) is next to die, after his drug dependency habit is exposed. Rodrigo’s girlfriend Alexandra (Asjha Cooper) is convinced Ollie is the killer, but Makani defends him. Then, when the two are on a date together, Ollie lets slip that he knows about Makani’s past, including her real name. How? His brother is a cop, and he had him run a background check on her.

Makani, outraged, takes an Uber home. There, she is attacked by the killer, who confronts with a headline about a young girl who was burned in a fire. Makani manages to get the better of the killer, but they run away before we can see their face. Because Makani knows that Ollie knows about her, she assumes everyone else was right: Ollie is the killer.

Makani also confesses to her friends that she pushed a girl into a bonfire during a hazing event at her old school, and was charged with assault.

WHAT IS THE THERE’S SOMEONE INSIDE YOUR HOUSE ENDING EXPLAINED?

Ollie is brought into custody but then released. Makani finds herself left alone in the school building, after the rest of the school leaves for a field trip to the Sanford family corn maze, and Makani misses the bus. When she sees Ollie’s car pull up, she flees and runs into her friend Caleb in the hallway. Before she can fill him in, Caleb is stabbed with a sword by the killer. At the same time, Ollie is running into the building, yelling Makani’s name to warn her—meaning the killer is not Ollie.

The killer, wearing a mask of Caleb’s face, presses the sword into Makani’s hands. Ollie calls for help. Makani sees that someone has spray-painted “SANFORD FAMILY BURNS” on the lockers, and (somehow) realizes that the killer is going to the corn maze next—where all her classmates are.

Zach calls Makani, and frantically tells her that the maze is on fire and that he’s going in to get his dad. Makani tells Ollie to drive his car through the flaming maze, in order to clear a path for everyone to escape. As they are helping students evacuate, they witness the killer murdering Zach’s father. Then the killer removes his mask, and it’s…

WHO IS THE KILLER IN THERE’S SOMEONE INSIDE YOUR HOUSE?

It’s Zach, the son of the wealthy farm owner. Zach explains in his little villain monologue that his intention was to teach his father (who is also a Nazi?) a lesson. Zach stabs Ollie and explains that he’s not a sociopath, and doesn’t want to feel ashamed just because he was born to privilege. Then he also talks a bit about how everyone is wearing fake faces, hence the whole mask thing. Oh, and also, he is going to frame Makani for everything, which is why he handed her the sword earlier. (Honestly, there are a lot of threads floating around here, and none of them really connect.) Then Ollie tases Zach, and Makani stabs him, and it’s over.

As a coda, we have a quick montage of Makani and Ollie going to prom together, and Makani’s remaining friends planning for their future, while Makani reads some of her poetry for the class at their graduation. The class applauds for her, and the movie ends.

Phew. Let’s hope that really is the end. These kids have been through enough.

Watch There's Someone Inside Your House on Netflix