Winter Moon by Dean Koontz
Eduardo, a retiree whose wife and son have died, lives on his isolated Montana ranch. His life is peaceful - if lonely - until he is awakened one night by a fearful throbbing sound and eerie lights in the lower woods. During the next several months, one mysterious and disturbing event follows another. Increasingly, he fears for his sanity and his life, until the terrible night when someone - or something - knocks on his back door...
Jack McGarvey, a Los Angeles cop, is hammered by submachine-gun fire when a madman goes berserk one lovely spring morning. He barely survives. His partner is not so lucky. Months later, still on disability, with no idea of when he might work again, with Los Angeles growing more violent by the day, he longs to move his family to a more peaceful place. Though he would do anything to protect his wife Heather and son Toby, Jack seems powerless and without prospects.