A team of scientists discovers Flora, a menacing asteroid racing toward Earth, and a high-stakes mission is unleashed to stop it. The space program calls up Robert Horton to lead the effort as Commander Jack Rankin, and he arrives at space station Gamma 3 with a clear, chilling warning: if he fails, there will be no chance of returning. Rankin is not alone on this voyage; he must cooperate with an old comrade, Richard Jaeckel who portrays Commander Vince Elliott, a man with a complicated past and a wary respect for Rankin’s command.
As the mission begins, Rankin commands a shuttle that descends to the surface of Flora to plant bombs and crush the asteroid before it can reach Earth. On the alien terrain, the crew encounters a strange, amoeba-like creature that clamps onto their vehicles and drains energy. The science officer, Ted Gunther as Dr. Hans Halvorsen, works frantically to bring back a sample in a sealed container, hoping to study its nature and perhaps find a weakness. But in a moment of frustration, Rankin shatters the container, allowing some of the green slime to cling to Halvorsen’s spacesuit, foreshadowing the creeping danger awaiting them.
The explosives detonate successfully, and Flora is destroyed, bright proof that a careful, risky plan can pay off. The crew returns to Gamma 3, where a ritual of decontamination begins. What starts as a routine procedure soon becomes a nightmare: the green slime evolves, and all the signs point to a new, more dangerous threat. An alarm sounds in the decontamination chamber, and when an officer opens the door, a hand is found to be dead, the victim of a lethal, unseen force. Among the officers, a one-eyed, tentacled creature reveals itself, capable of discharging powerful electricity.
The crew quickly learns that conventional weapons won’t halt this enemy. The creature’s electrical discharges cause its blood to spawn more of itself, rapidly multiplying into a swarm that could overrun Gamma 3. Dr. Halvorsen is killed while attempting to contain the creatures, underscoring the human cost of the crisis.
Rankin, determined to see the mission through, refuses to abandon his post even as the situation spirals out of control. He orders an evacuation and orchestrates a desperate plan to set Gamma 3 to burn up in Earth’s atmosphere, intending to purge the station and the surrounding contamination. Elliott returns to aid his friend, but sacrifices himself in an effort to save Rankin, dying in the line of duty.
In a final, tense sequence, Rankin engineers a crash landing and escapes with Elliott’s body aboard a shuttle as Gamma 3 succumbs to the flames, destroying the remaining green slime and ending the immediate threat. The mission is logged as a success in the face of overwhelming odds, and Rankin recommends the highest possible citation for Vince Elliott posthumously, honoring a colleague who gave his life in the line of duty.
The ordeal on Flora and Gamma 3 paints a stark portrait of courage under pressure, where human ingenuity meets the unknown and a team’s resolve is tested to its limits. The film closes on a somber note of tribute and a reminder that even in victory, sacrifice often accompanies the pursuit of survival.
