A missing Creator. An army of mechanical zombies. And a devastating secret that will destroy everything. Adal, Arija and the rest of their team are happy to be back home in the World Machine. But before they can get comfortable, things start to heat back up between the Dwellers that live in the Machine and those that would see it destroyed. Webley is the only one who can quell the buzz of war, but the Creator has gone missing. That's when the screaming starts. Reports of a masked creature spread like the plague. Then a virus breaks out in the Machine. A virus that turns the Dwellers into Zombies. Can the team unmask the doctor and find a cure before the virus destroys the world?