Sean leads a solitary life in a caravan nestled within a forest, with only his cat, Kaspar, for companionship. His days are consumed by the pursuit of alchemical experiments, guided by an ancient book, though remarkably, his efforts yield little success amidst the mysterious sounds that permeate the woods. With his stock of pills running low—crucial for maintaining his mental balance—Sean becomes increasingly anxious, suspecting he is being watched. In his paranoia, he locks himself inside the caravan, armed with an axe, as he awaits a visitor.
That visitor turns out to be his friend, Cortez, who arrives with supplies but bears disappointing news: he cannot locate the pills Sean desperately needs and refuses to traverse the three-hour trip back to his place. The absence of these pills triggers a rapid decline in Sean's mental state, spiraling him into paranoia and dread.
His mindset deteriorating, Sean attempts to catch animals as part of his dark plans, setting traps in the forest. Venturing out onto the lake in his rowboat, he declares his intention to summon a demon that very night, proclaiming a willingness to offer whatever the demon desires, including his own body and teeth. Sean's first victim, an unsuspecting possum, finds its way into his traps, leading to a grim fate that he seems unbothered about. That evening, he enkindles a fire, entreating a being named "Belial," proclaiming his remorse for his human form while invoking Latin passages from his alchemical tome.
However, as ominous noises echo from the forest, fear envelops him, driving him back into the safety of his caravan. Lighting numerous candles to ward off the darkness, Sean pursues his grim activities further, ultimately killing the possessed possum with a knife.
Upon Cortez's return to the cabin for a stay, he is taken aback by Sean’s increasingly erratic behavior and the gruesome sight of the dead possum. Sean’s heightened agitation leads him to threaten Cortez with a knife, forcing him to leave and feeling a deep sense of betrayal. Later, Sean stumbles upon Cortez’s damaged car deep in the forest, discovering a cross necklace and a tooth lodged in a tree engraved with the words "PAY UP."
Night falls, and as Sean engages in occult practices, burning his alchemical papers, he is met with a bloodied Cortez, eyes alight with a ghastly glow. Cortez shares tales of a malevolent force dwelling in the forest, claiming it demands recompense for all that Sean possesses.
In a harrowing turn of events, Sean discovers Cortez's lifeless body and inters him. As despair settles in, he resorts to extreme measures, using pliers to extract his own teeth. That night, he defiantly calls out to the demon, offering it his tooth in hope of appeasement, only to be met by an unsettling response from the depths of the forest.
Sean’s descent into madness accelerates as he finds himself drenched in blood, engaging in violent acts against himself and consuming the raw remains of the possum. In a moment of realization, he discovers his cat has vanished. Desperately searching for Kaspar, Sean's voice distorts, blending with the haunting howls of the demon echoing through the trees.
In a final act of desperation, Sean plunges beneath the lake's surface, thinking he has conquered the demon. Yet, joy morphs into dread as he hears the sorrowful whimper of his beloved cat mixed with the chilling howl of the dark entity lurking in the shadows of the forest.
