After the exodus from Earth, humanity split into two major groups who, while not exactly fond of each other’s company, were never in open conflict.
This all changed when an unidentified alien vessel crash-landed on planet Tartarus, right on the border of a contested region. Neither party agreed to give up the mysterious cargo, which lead to an all-out war, fueled by centuries of ideological hatred.
Meanwhile, back on Earth, the last of the planet's inhabitants have emerged from the ashes of what was once their home. Robbed of any semblance of security, with no future to behold, they demand retribution from the original colonists for dooming their homeworld. Things are about to get ugly.