When members of the Alliance are poisoned by an unknown substance, Zee discovers there's only one place to find help: Dianoia, the deadly catacombs under an invisible city. But when Zee, along with her friends Erik and Morgan embark on their quest, they quickly realize that the lives they need to save may just be their own. If their adventure doesn’t destroy themà the Consortium and the diabolical Doctor Twice are lurking in the wings to finish the job.