In Broken Mathematics — Gregory Ashe

Months have passed since Alex stopped the monster known as the eater from ravaging the small town of West Marshall. Just when life seems to be settling into something normal, an FBI agent shows up on Alex's doorstep, wanting to know where he was the night Melanie Evans died. As Alex scrambles to cover the trail that connects him to the string of deaths in West Marshall, another quickener arrives in town, and the dead begin to rise. Alex must find this new quickener, and fast--before he and his friends are killed.