In a future when natural resources are in short supply, advanced technology enables spacecraft to tow asteroids across the solar system for mining purposes. "The Spirit of Forty-Nine" is just two weeks away from hauling Asteroid MT27 into Earth orbit. However, an unknown killer aboard the ship is taking out crew members one by one, including Captain Cyril Jackson. First Officer Daryl Boden assumes command. Back on Earth, Boden's ex-wife Marilyn, a former anti-terrorist agent, is coaxed back to work to pursue the deadly eco-terrorist Lopez. On the spaceship, more crew members are murdered until Flight Specialist Joe Schneider discovers the horrifying truth. The mission has been sabotaged, causing the asteroid to head for a catastrophic collision with Earth.