Charlie McFadden, the last of the bounty hunters, is tasked with eliminating the remaining Critters, alien pests that have terrorized Earth. However, just before he completes his mission, he is interrupted by the intergalactic council, who decides to preserve the last two eggs for scientific purposes. They are sealed in a capsule, and Charlie accidentally gets trapped inside. Decades later, a spaceship named the Salvage 1 comes across the capsule drifting in space and brings it aboard. The crew, expecting valuable cargo, instead unleashes the deadly creatures.

As the Critters begin multiplying and wreaking havoc on the ship, the crew must navigate their plans for survival. Complications escalate as they discover the ship's systems are failing, and its corporate overseer has ulterior motives. Amidst chaos and growing mistrust among crew members, Charlie wakes up from stasis and teams up with the others to devise a plan to stop the Critters before they reach Earth. In a race against time, they must battle not only the ferocious aliens but also the perilous environment of deep space.