Newlyweds Bea and Paul venture into the secluded woods for a romantic honeymoon at Bea's family cabin. Initially enchanted by their tranquil surroundings and each other's company, their idyllic retreat turns unsettling after a strange nighttime disturbance. Paul finds Bea sleepwalking in the forest, disoriented and distant. The following day, her odd behavior escalates; she forgets basic details, exhibits uncharacteristic physical signs, and becomes increasingly evasive about her whereabouts. Dismayed and confused, Paul attempts to rationalize the situation, attributing Bea's conduct to stress or fatigue.

As days pass, Paul's concern grows into suspicion and paranoia. He discovers disturbing clues that suggest an ominous force at play, which compels him to confront Bea. His attempts to seek help are thwarted by their isolation and the peculiar behavior of visiting neighbors. The once loving and open couple find themselves trapped in a psychological and emotional battle against an inexplicable horror that threatens both their sanity and survival. The tension between them mounts, pushing their relationship to the brink as Paul struggles to understand the sinister transformation overtaking Bea and the true nature of the lurking menace in the woods.