Mankind has been infected with a virus that lies hidden within our DNA until a temporal marker is reached, then works at breaking down the body until nothing is left but dust and bone. Yanked out of retirement, Jennifer must go back in time once more to find the point of infection and stop it, or else Mankind will be forever lost and the fleet of colony ships entering our part of the galaxy will be able to just move in and set up shop without a shot ever being fired.