On the surface, Shale Cove was the perfect tropical paradise — uninhabited, untouched, and only recently rediscovered after being omitted from nautical maps for over seventy years. When tech billionaire Erik Dalmar purchases the island for a luxury resort project, he sends an elite scouting team ahead: architects, divers, marine biologists, and a few ex-military contractors for “safety.” Among them is Dr. Callie Arden, a deep-sea geologist haunted by a shipwreck that claimed her brother’s life. She hopes the assignment will offer closure. Instead, it opens a door to hell.
As the team begins surveying the crimson-tinted shoreline — its sands unusually dark, its waters tinged with rust — strange phenomena start to unfold. Equipment malfunctions. Radios go silent. The crew experiences shared hallucinations. One diver surfaces screaming about “the voices in the trench.” Another goes missing entirely, leaving only a wetsuit — torn and blood-soaked — floating near the reef. The island holds an ancient legend, one passed down by a forgotten Polynesian tribe: “When blood stains the sea, the sleepers shall rise.” Callie finds cave etchings depicting creatures half-man, half-crustacean, crawling from the ocean floor to reclaim the land. Dismissed as folklore, the warnings come alive when the first night falls.
A storm traps them on the island. One by one, the crew is hunted by something unseen — dragged into the surf, torn apart, or simply vanished. What they face is no ordinary predator. From the depths emerge The Drowned Ones — humanoid beings mutated by centuries of exposure to a rare, parasitic coral that feeds on blood and memory. Once sailors, pirates, even victims of ritual sacrifice, they’ve become guardians of the cursed shoreline. Callie discovers that the island lies above a massive undersea crater — a dormant volcanic rift pulsing with geothermal energy. The red hue of the beach? Iron-rich blood from hundreds, maybe thousands, of ancient sacrifices that have seeped into the seabed. The Drowned Ones aren’t just killing — they’re feeding. Evolving.
Erik, refusing to abandon his investment, tries to flee with a private yacht, only to be dragged into the depths live on drone footage. The survivors, now only Callie and an ex-SEAL named Boone, have one chance left: collapse the crater using explosives left from the geothermal survey. But the plan comes with a cost — one of them must manually detonate the charge. Callie chooses to stay, finally facing the watery terror that took her brother. As Boone escapes on a rescue chopper, the ocean implodes in a crimson vortex. But even in death, the sea remembers. And when a lone piece of coral washes ashore days later on a crowded tourist beach… the red tide returns.
