In the future, after global warming, Earth is covered by ice and snow in an Ice Age. The survivors live in facilities underground named Colonies. When people from Colony 5 release a distress signal, the leader of Colony 7 Briggs organizes an expedition with Sam and Graydon to investigate what has happened to their acquaintances. Briggs leaves the scientist Kai in charge of the group, disappointing his former friend Mason that expected to be assigned to the position. When they get there they find the that the colony has fallen and there is a whole new enemy that they have to face on their way back.