Harbinger Down

In 1982, a Soviet moon lander crashes into the icy waters of the Bering Sea, setting a haunting precedent for what lies ahead. The discovery hints at a dangerous mystery beneath the ice that will reappear decades later.

Biology professor Stephen joins graduate students Ronelle and Sadie on an experimental voyage to study warming oceans and whale populations. Graff steers the weathered Harbinger, a rugged trawler, launching an expedition into uncharted seas.

That night, a hum and sonar ping lead Sadie to the buried lander. Inside, a cosmonaut lies dead, and Sadie salvages a skin sample, triggering a tense debate about who owns the discovery.

Sadie examines the lander and uncovers tardigrades that survived by mutating under cosmic radiation. The creatures gain the ability to shapeshift, turning the mission into a perilous encounter with alien-like biology.

The cosmonaut’s body vanishes and Stephen becomes exposed to the tardigrades through careless handling. He falls into a feverish, dangerous state as the infection begins to spread aboard the Harbinger.

Organisms sprout from Stephen’s back and dark alien liquid sprays across the deck. Sadie and others scramble to contain the outbreak, using liquid nitrogen to freeze the crew and the lander in hopes of halting the spread.

Dock shows early signs of infection and Svetlana isolates him in a cage, contemplating incineration. The plan is complicated when Dock itself sprouts tendrils, exposing Svetlana’s true allegiance.

The creature’s advance cripples the ship’s systems as the backup battery fails. Atka is killed by the mutated entity, and Svetlana’s role as a spy is confirmed in a brutal turn of events.

Svetlana reveals that the tardigrades are part of a Soviet experiment to engineer radiation-resistant cosmonauts and plans to sink the Harbinger after boarding a nearby submarine. The mutating organism continues to seize control of the ship.

The creature lashes out, dragging Ronelle and Svetlana into the dark below the deck. The crew scrambles for explosive charges Svetlana hid throughout the ship, racing to stop the spread.

The tardigrades consume a cargo of crab, filling the ship with a fishy scent and closing in on the survivors. Sadie escapes the expanding swarm, but Graff is infected and tasks Bowman with the grim duty should it come to it.

Big G sacrifices himself, killed by Svetlana as she fights for control. Graff, mortally wounded, instructs Sadie to scuttle the vessel to save herself.

Sadie pilots the Harbinger toward a looming iceberg as the creature bursts onto the deck. Graff's dying guidance pushes her to risk everything to salvage herself.

A rescue helicopter closes in, its rotor wash reaching the Harbinger as Sadie collapses on the ice. The vessel’s silhouette fades into spray and snow, leaving the promise of rescue at dawn.