Tim wakes from a ten-year coma to find a world that has been transformed by catastrophe. His wife — visibly pregnant — explains what has been happening: rifts have been opening across the globe, releasing creatures that resemble humans in shape but in nothing else, and four hundred and twenty days into the crisis, the city hospital has become one of the last places where people can still hold on. Before Tim can process any of this, or ask the most pressing question forming in his mind, the alarms go off. Monsters are in the building. His wife pushes him clear and sacrifices herself in the doorway. Tim loses consciousness. He wakes in an unfamiliar room. There is a door in front of him — but something else in the room with him as well.