The McClellands are enjoying a lazy summer vacation at the beach when they are lured from our world into Ixeos, an alternate Earth. Finding themselves lost in a maze of tunnels under Paris and surrounded by strangers, they discover that they have been brought to Ixeos for one purpose: to take the planet back from humanoid aliens who have claimed it. With the aid of the tunnels and a mysterious man named Landon, the teens travel the world seeking the key that will allow them to free Darian, the long-imprisoned rebel leader. The aliens aren't the only problem on Ixeos -- the McClellands have to deal with brutal gangs, desperate junkies, and a world without power, where all the technology is owned by the aliens, and where most of the population has been killed or enslaved. The worst part? There's no way home.