After an alien species destroys most of the human race, a lone military ship, Horizon, is sent back to Earth to exterminate the invaders. Tensions, tempers, and sexual appetites heat up amongst the crew as they realize that they may not survive the ordeal. Their mission turns into a war of survival as they engage enemy ships, fire fights, a beautiful mind-controller, vicious "Crawlers," and even each other. Who will be more of a threat: their fellow crew or the creatures lurking outside?