Legends have told of an elite group of warriors known as Sentinels, the only humans capable of defeating the dreadful giant beasts called Ravenii. Eventually, these legends faded to myth and were only spoken about in children’s fairy tales. As time went on, people no longer warred against monsters but instead turned to battling one another.

Now the unthinkable has occurred: the Ravenii have returned to this land through strange, arcane portals, with bloodthirsty new allies trailing in their wake. Avil, the last of the ancient order – and the hero you will play – must use everything in his arsenal to slow the oncoming storm and rescue as many people as possible in the land of Dolorum.

Dolorum is besieged on all fronts and Extinction's campaign tells the story of the Ravenii's relentless march through the country. Avil and his ally, Xandra, have to work together with King Yarrow to try and stem the tide. Meanwhile, humanity is making one last-ditch effort to understand the Ravenii and to make the alien technology their own. Failure here means the end of everything.