Three-hundred years after an alien invasion, the remnants of human society thrive in Pacifica, an underground colony on the edge of the Pacific Ocean. During a routine trip topside to look for supplies, two men go missing, while another contracts a virus from the surface and unknowingly unleashes a contagion upon the colony. A sickness spreads that transforms children to alien hybrids who then attack and kill the adults. 

As the pandemic worsens, the new governor orders everyone to evacuate to the Orca—an unfinished prototype submarine she’s been preparing to house the colony. Meanwhile, the head of security struggles to save the citizens of Pacifica from the encroaching creatures, and a young man on a quest for purpose finds it in the chaos. Some will survive against all odds, some will die as heroes, but one thing is certain—Pacifica will fall.