To the Kleese, the Earth is nothing more than a planet full of conscripts to fight in their wars of aggression against other planets. The Kleese are one of three large Galactic Empires that control the majority of the galaxy. To them, Earth is a dangerous planet due to the aggressiveness of the humanoid species that inhabits it. This is a species that cannot be allowed to go out into the galaxy. Once they have taken their conscripts, the planet will be destroyed.
Mason Randle controls the Smithfield Mining Corporation. His main base is inside the asteroid Vesta, and he will do everything in his power to save what is left of the human race after the Kleese attack.
Lieutenant Wade Nelson is a marine taken as a conscript by the Kleese. His primary goal is to find a way back to Earth. In the meantime, he will fight in the wars the Kleese are involved in until he knows enough to take the fight to the Kleese themselves. He will bid his time and someday find a way back home for himself and his marines.