Rebekka Moon by Michele Spence

The Branch:  a quiet place, a sleepy Nebraska town, a place where nothing had happened---not for decades.  Until it began...

First it was the children - their "innocent" pranks, their "childish" cruelties, transformed overnight into unspeakable acts of torture, madness, and sudden, hideous death.  

Then it was more...much more.  The town was swept into a current of irresistible evil... a tide of darkness that swirled around the solitary figure of a frail sixteen year old girl.  Could she control their bodies?  Possess their minds?  Could anyone grasp her secret and stop...