What Keeps You Alive (2018) Plot Summary & Ending Explained

Jackie decides to take her wife, Jules, to a secluded cabin to celebrate their first anniversary, but things take a dark turn when Jackie’s childhood friend, Sarah, visits and calls Jackie by her former name, "Megan." This revelation raises suspicion in Jules, who confronts Sarah and her husband, Daniel. During their discussion, Sarah recounts a tragic incident involving a girl named Jenny, who drowned when they were children, and is taken aback when she learns that Jackie never mentioned this tragedy. Jackie later confesses that she withheld the information because she believed she was to blame for the incident, despite being cleared of any police wrongdoing. This moment of vulnerability leads to a tender moment as Jules comforts Jackie.

However, the celebration turns sinister when Jackie suddenly pushes Jules off a cliff while they admire the beautiful wilderness view. After returning to the cabin, Jackie rehearses a tearful call to the police, reporting Jules' supposed death. Unbeknownst to her, Jules, though gravely injured, is still alive. Upon discovering that her wife has escaped, Jackie frantically searches the forests, pleading for Jules' forgiveness. Jules contemplates revealing herself but becomes wary when Jackie’s true intentions become apparent — that her concern is merely an act. Ultimately, Jules manages to reach safety at the house, tending to her wounds and attempting to escape across the lake in a boat, but Jackie catches up to her.

Daniel witnesses the escalating tension, and despite Jackie threatening both him and Sarah, Jules insists they come for dinner, wanting to show that everything is fine. However, Jackie reveals her true feelings, declaring that she never loved Jules and plans to kill her for the life insurance money. The plot thickens when it's suggested that Jackie was involved in Jenny's death. As Sarah grows increasingly suspicious of Jackie, the tension culminates in a horrifying confrontation where Jackie murders Daniel and fatally assaults Sarah. She then coerces Jules into helping dispose of the bodies, revealing a box filled with necklaces belonging to her deceased former wives, hinting at Jackie's dark past.

The situation escalates as Jackie drives Jules back to the cliff’s edge with the intention of finishing what she started. However, Jules fiercely resists and manages to incapacitate Jackie with a tranquilizer dart, narrowly escaping in a car. Still, she bravely returns for a confrontation, which leads to a brutal struggle where Jackie eventually gains the upper hand and throws Jules over the cliff once more. Believing she has succeeded in her deadly plans, Jackie contacts the police.

In a shocking twist, as Jackie injects herself with insulin due to her diabetes, she begins to feel unwell. She soon realizes that the insulin has been tampered with, spiked with hydrogen peroxide, leading to deadly blood clots. In her weakened state, she collapses in the woods and ultimately dies from a stroke.

Meanwhile, below the cliff, Jules lies seemingly lifeless with eyes wide open. Yet, as the camera pans over the sprawling trees, a sharp intake of breath is heard, hinting at her miraculous survival against all odds.

At the film’s climax, Jackie, who has revealed herself to be a killer with a dark past, continues her murderous spree in the woods, motivated by a twisted belief that killing keeps her alive, as her father once told her. She has murdered multiple women before Jules, including her childhood friend Jenny, whose death she caused during a past lake incident. When Jackie pushes Jules off a cliff and begins mimicking her screams of distress, it’s clear she has an underlying motive: to eliminate her wife and claim her life insurance, just as she did with her previous wives. However, Jules fights back and manages to kill Jackie by mixing hydrogen peroxide with her insulin, causing her to suffer a fatal stroke—an act of revenge that persists even after her death. This twist highlights the film’s theme of survival through murder, as Jules’s own demise becomes her act of vengeance.

In the final moments, Jackie, now dying in the woods, searches for help but succumbs to a stroke, disoriented and defeated. The symbolic image of a bear she once shot when it was innocent underscores her senseless violence since childhood and her inability to truly stay alive, despite her killings. The scene’s mysterious sound of Jules gasping for air raises questions—did she survive her fall or not? Given her severe injuries, it’s unlikely, and the scene leaves it open to interpretation. It suggests that Jules, having lost her fight against Jackie, might be suffering painfully in the woods, unable to get aid, just as the animal she shot was left to suffer. The film’s ending is layered with symbolism, emphasizing themes of self-destruction, the illusion of survival, and the tragic cycle of violence. The twists, especially Jackie's murderous past and Jules’s revenge, make the story a haunting examination of how the desire to survive can lead to destructive consequences for everyone involved.