This Present Darkness (Darkness #1) by Frank E. Peretti

Ashton is just a typical small town. But when reporter Marshall Hogan and pastor Hank Busche begin to compare notes, they suddenly find themselves fighting a hideous plot to subjugate the townspeople--and eventually the entire human race.

A fast-moving, riveting thriller, This Present Darkness offers a fascinating glimpse into the unseen world of spiritual warfare - and the power of prayer.