The year is 2217, and Commander Frank Yamane is the captain of the stellar cruiser, Corona, stationed at Saturn's moon, Titan. Having been in the military for most of his life, he is a battle-hardened man who has experienced a series of personal tragedies, including the loss of his beloved wife, Liana. The inability to prevent her death has left him feeling guilt-ridden, and plagued with doubts regarding his ability to lead others. It is these same experiences, however, that have also prepared him for when humanity needs him most−when an alien race known as the Deravans attack the Earth without mercy. Knowing he cannot stop them alone, Yamane has no choice but to seek the assistance of an enemy he helped defeat in a war ten years before. The problem is, Commander Yamane knows they have every reason not to come to Earth's rescue.