The cinematic journey unfolds as Thomas Wake, a seasoned lighthouse keeper, begins a four-week stint with his new assistant, Ephraim Winslow. Settling into their isolated quarters, the oppressive environment sets a somber and foreboding atmosphere. Wake, an experienced keeper, has witnessed many colleagues come and go, but there’s an unusual aura surrounding this newcomer that catches his attention. On the other hand, Winslow finds himself intrigued by a hidden mermaid figurine, which adds an air of mystery to the narrative.
As the days go by, Wake offers Winslow a taste of liquor, yet he declines, opting to tackle the arduous responsibilities of their job. The towering lighthouse casts an imposing presence, overshadowing the desolate island. One night, Wake mysteriously vanishes into the shadows, leaving behind only whispers and intrigue. Winslow, sensing that something is amiss, feels compelled to approach the rocky shoreline, where he stumbles upon a shocking sight: a lifeless body adrift in the water.
With each passing day, Winslow becomes haunted by vivid visions of a mermaid, complemented by an ethereal melody that plays in his mind. Wake’s ominous presence looms larger, accompanied by cryptic admonitions, particularly emphasizing that seagulls must never be harmed. He believes these birds carry the souls of lost sailors, making them sacred. Winslow's increasing fascination with the mermaid figurine becomes a symbol for his deepest desires, pulling him further into a web of intrigue.
As tension rises and Winslow’s curiosity escalates, Wake’s nighttime rituals deepen the enigma. The question that echoes throughout their time together is: what secrets lie behind the lighthouse’s formidable façade? As Winslow’s dissatisfaction with his situation intensifies, Wake’s condescending demeanor becomes a frustrating thorn in his side. The climax of their tension arrives when Wake carelessly drops Winslow mid-task, bringing forth a familiar half-blind seagull that seems to mock him. In a moment of defiance, Winslow demands that Wake refer to him by his first name, rejecting the dehumanizing term “dog.”
Their conversations drift to past encounters, with Wake sharing tales of his former wickie’s fantastical adventures involving mermaids and sirens. The monotony of their routine is occasionally interrupted by moments of tension, such as when Winslow attempts to seek solace alone only to be startled by Wake, who approaches him naked toward the flickering light. Later, a chance encounter with a seagull sends Winslow into a frenzied rage, culminating in a violent assault on the bird against the unforgiving rocks.
As their stay on the island nears its end, Wake senses an oncoming storm and suggests they drown their sorrows before their departure. They barricade themselves in, succumbing to a night of relentless drinking, which only exacerbates their brewing conflict over ascension to the lighthouse. The following morning greets an unkempt Winslow as he returns to his chores, confronting a series of unfortunate mishaps, including a messy chamber pot incident that splatters waste back onto him. Amidst the intensifying rain, Winslow encounters a mysterious young woman, seemingly a mermaid, washed ashore. As she awakens and emits a haunting siren's cry, surprise and shock wash over him.
Throughout the storm that follows, Wake grows increasingly pessimistic about their chances of rescue, leading both men to venture into the rain for “rations,” only to become further intoxicated. The night spirals, filled with heated arguments where Winslow's frustration reaches a boiling point, climaxing with cruel insults hurled at Wake’s cooking, invoking Wake’s curse upon Winslow that beckons the anger of Neptune and heralds chaos to unfold.
Throughout the night, Winslow’s repeated attempts at escape are foiled by Wake, who brutally destroys the lifeboat with an axe, igniting a frantic chase that drives Winslow to the brink of madness. Their words, laced with venomous tensions, slowly peel back layers of Wake’s true depravity. As the storm rages outside, it mirrors the turmoil within their souls, revealing Wake’s gruesome past deeds including the murder of a gull and the real Ephraim Winslow.
As dawn breaks, the culmination of their tumultuous night arrives. The argument simmers into a volatile explosion, with Winslow unleashing his pent-up rage on Wake, who provokes him mercilessly. In a fierce struggle, Winslow wrestles Wake into submission, forcing him to act like a dog before burying him momentarily. Yet, this fleeting victory is shattered when Wake violently re-emerges, axe in hand, and sinks it into Winslow’s shoulder. In a tragic twist, overwhelmed by desperation, Winslow counters and delivers a lethal blow to Wake's head.
Claiming the keys, Winslow ascends to the top of the lighthouse, where he gazes longingly into the light. His laughter transforms into madness as he reaches for the beacon, only to lose his footing and tumble down the stairs in a grotesque fall. When the sun rises over the desolate shoreline, Winslow (actor name) lies motionless on the jagged rocks, an unsettling image of vulnerability. The cacophony of screeching seagulls accompanies this grotesque display as they feast voraciously upon him. Paralyzed by dire circumstances, Winslow's unresponsive body underscores the brutality of his environment, with the air thick with decay and despair as his fate unfurls.
