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The Ending Of What Lies Below Explained

It's never easy when a parent starts dating someone new. And as hundreds of Lifetime Original Movies have taught us, it's even harder when that someone is hiding a dark and terrible secret. The horror flick What Lies Below, which is currently blowing up on Netflix, plays on the classic tropes of a domestic thriller. However, once you see under the film's familiar surface, you realize that nothing is quite what it seems.

Teenager Libby (Ema Horvath) comes home from summer camp to find that her mother, Michelle (Mena Suvari), has moved her new boyfriend into their lakefront home. John (Trey Tucker) is handsome, charismatic, and smart. Not only is he now living in Libby's house, but he's also turned the basement into a makeshift laboratory. Libby is immediately suspicious that John may not be the great guy her mother purports him to be. But Michelle doesn't want to hear any bad news about her new boyfriend. As John's behavior becomes increasingly strange and alarming, Libby is left wondering exactly what he has planned for her and her mother.

While the movie has a setup that will sound familiar to many, the grim conclusion offers a truly unique twist on the genre. Here's everything you need to know about the ending to What Lies Below.

John's behavior begins to worry Libby

Although it takes a while for his true intentions to reveal themselves, John's behavior is a bit off right out of the gate. When they first meet, he gives Libby a bracelet, the stones and symbols of which he claims are related to ancient fertility rites. It's an odd choice of gift for the teenage daughter of your girlfriend, but he claims he chose it because he knows Libby has an interest in archaeology.

John uses Libby's scientific inclinations to try and bond with her. He tells her that he's part of a research team that's "scattered around the area" that is trying to help increase the adaptability of freshwater animals so they can live in saltwater environments, as global warming is causing an increase in salination. Later, he shows her his basement lab where he breeds lampreys, and even takes her out onto the lake to help him catch some.

During their boat trip, Libby suddenly gets her period. John reaches out to grab a loose lamprey and grazes between her legs. He apologizes profusely for the inappropriate and non-consensual touch, claiming that it was an accident. However, he follows it up by licking the blood off his fingers, which rightfully disturbs Libby.

While she was starting to warm up to him a bit before, after the incident in the boat, Libby becomes extremely weary of John. Those concerns are only escalated further one morning when Michelle, who is extremely ill with what she claims may be morning sickness, asks Libby to get her supplies from the pharmacy in town. While there, Libby sees John canoodling with another woman and wearing clothing that's very different from his usual style. Libby is now certain that something is very wrong.

Michelle is in over her head

Later that night, Libby confronts John and Michelle. She tells her mother the details about the inappropriate incident on the boat, but Michelle doesn't want to hear it. This causes Libby to lash out by revealing that Michelle is 42 years old, and not 35 like she'd previously claimed. In regards to Michelle's pregnancy, Libby tells John, "So, sure hope you weren't planning on having another one."

This revelation upsets John more than any other part of the tense confrontation and he storms out of the room. However, later that night, Libby is drawn to her mother's bedroom by what sound like cries of distress. When she peeks through the door, she sees John on top of Michelle in bed. As she looks at his bare back, she notices that it appears to be growing scales.

Libby goes to hide in her room but then notices that the lights are on in the basement. When she goes down, she finds her mother unconscious and restrained in a tank of water. Unable to free her, Libby hides when she hears the footsteps of something coming down the stairs. That something is John. Except now, he's in his true form.

John is not actually a human. Although it's never revealed exactly what he is, he appears to be some kind of aquatic monster that is able to take human form. John's experiments were never about helping lampreys and other animals better adapt to saltwater conditions. They were about adapting his own species to living in a more salinated world. As Libby observes while he walks across the partially flooded basement floor, John's feet sizzle when he comes in contact with saltwater.

And now that Libby knows what John is, she's also about to find out what he has planned for her.

The nightmarish ending of What Lies Below

While Libby watches in horror, Michelle suddenly gives birth to some kind of creature. Using Michelle to produce more creatures, presumably ones he hopes will be more adaptable than the previous generation, has been John's plan all along. It's why he was so upset to learn that Michelle is older and potentially has fewer years of fertility left. His interest throughout the film in Libby's own fertility (remember that bracelet?) also implies that he has something similar in mind for her.

Libby tries to save her mom and flee, but she's ultimately knocked out and apprehended. When she comes to, she's tied to a chair in a basement. There are other men there — John's fellow "researchers" that he alluded to earlier — who begin tearing apart the drywall. Before she can see what's behind the walls, John appears. He opens Libby's mouth and she sees a glowing blue light emerging from his throat. After he spits it into her mouth, everything goes black.

When Libby wakes up, she's in a sealed tank of water. As the camera pans out, we see that Libby's tank is but one of many and that each contains the partially cocooned body of a young woman. As the remarkably bleak ending suggests, John and his cohort of freshwater monsters have been kidnapping women (such as the one Libby saw John with earlier) and are using them in their experiments to try and produce a new generation of their species that can live in saltwater environments

Libby was right to be suspicious of her mom's new boyfriend. Unfortunately for her, she learned too late exactly how dangerous he is.