Following a nuclear war that drove the survivors to seek refuge underground for 100 years, humanity is finally making a comeback-or so it appears. As people work together to rebuild their communities, both big and small, little do they realize they're facing an even bigger threat than the one that nearly doomed their civilization. And this time the danger isn't from Earth.

Fleeing a deadly global conflict on their own planet, a steady stream of refugees from Venus is showing up on our planet, wreaking havoc wherever they go. An elite group known as Sentry is charged with fighting the aliens and keeping their existence a secret from the general public. While Sentry has been successful so far, the Venusians are about to raise the stakes.

Foremost amongst the Sentry agents is Ryland Ambrose, an elite warrior with exceptional abilities who was recruited into the program as a young child. As he battles against the increasingly dire alien menace, Ryland is also wrestling with a host of internal demons. If he fails to overcome them, not only could his own life be in peril, he could also jeopardize the entire mission, plunging Earth once more into a fiery maelstrom of chaos and death.