In the mid-23rd century, Darwin, Australia, stands as the last human city on Earth. The world has succumbed to an alien plague, with most of the population transformed into mindless, savage creatures. The planet's refugees flock to Darwin, where a space elevator--created by the architects of this apocalypse, the Builders--emits a plague-suppressing aura.

"The hunt is on for the mysterious keys left by the alien Builders. While Skyler's team of immune scavengers scatters around the disease ravaged globe in search of the artifacts, Skyler himself finds much more than he expected in the African desert, where he stumbles upon surprising Builder relics-- and thousands of bloodthirsty subhumans. From the slums and fortresses of Darwin to the jungles of Brazil and beyond, Skyler and company are in for a...