Forced underground by the next ice age, a struggling outpost of survivors must fight to preserve humanity against a threat even more savage than nature.
The wanted criminal Riddick arrives on a planet called Helion Prime, and finds himself up against an invading empire called the Necromongers, an army that plans to convert or kill all humans in the universe.
Four waves of increasingly deadly alien attacks have left most of Earth decimated. Cassie is on the run, desperately trying to save her younger brother.