A huszadik század második felében zajló hidegháborúban hatalmas rivalizálás dúlt az űrprogram terén a Szovjetunió és az Egyesült Államok között. Alekszej Leonov harci pilóta készen áll, hogy az első ember legyen, akit kilőnek az űrbe, ám mindez ismeretlen veszélyeket és akadályokat tartogat számára.

After spending several months in an orbiting lab, three astronauts prepare to return to Earth only to find their de-orbit thrusters won't activate. After initially thinking they might have to abandon them in orbit, NASA decides to launch a daring rescue. Their plans are complicated by a hurricane headed towards the launch site—and a shrinking air supply in the astronauts' capsule.

A strange signal arrives on the Earth disturbing all communications, while an UFO appears above the Antarctic sea. Captain Alex Hamilton is sent with his spaceship and crew to the space outside the Solar System to find the origin of that signal. They reach an unknown planet where a giant robot enslaved a whole population of humanoids by taking their psychic energies.

In the near future, a space station dubbed Earth II is built for the purpose of scientific research and world peace. However, that peace is shattered when the Chinese send up a nuclear bomb that is orbiting just a few miles away from the station. Can the crew disarm the bomb before it detonates, not only destroying the station but setting off World War III?