The Final Evolution (Avery Cates, 5)

The world is dying. With avatars replacing humans and the birth rate non-existent, the human race is almost extinct. In the end, it comes down to Canny Orel; Avery's long sought after nemesis -- transformed now into something other than human.

Orel might hold the secret to humanity's salvation, if he can be convinced -- or forced -- to relinquish it. And when Cates chances on a way to trick his old master, he suddenly has a choice to make: get his long-delayed revenge, or save the world.