In the fourth and final season of "The Strain," the world has fallen into darkness under the rule of the Master and his strigoi army. The remnants of humanity are struggling to survive in a nightmarish dystopia. Dr. Ephraim Goodweather, Fet, Setrakian, and their allies must rally for a final stand against the overwhelming forces of evil. As the stakes reach their highest, they confront old enemies, forge new alliances, and make unimaginable sacrifices in a last-ditch effort to save humanity from extinction.