Dreamcatcher
by Stephen King
Set near the fictional town of Derry, Maine, Dreamcatcher is the story of four lifelong friends: Gary "Jonesy" Jones, Pete Moore, Joe "Beaver" Clarendon and Henry Devlin. As young teenagers, the four saved Douglas "Duddits" Cavell, an older boy with Down syndrome, from a group of sadistic bullies. From their new friendship with Duddits, Jonesy, Beaver, Henry and Pete began to share the boy's unusual powers, including telepathy, shared dreaming, and seeing "the line", a psychic trace left by the movement of human beings.
Jonesy, Beaver, Henry and Pete reunite for their annual hunting trip at the Hole-in-the-Wall, an isolated lodge in the Jefferson Tract. There, they become caught between an alien invasion and an insane US Army Colonel, Abraham Kurtz. Jonesy and Beaver, who remain at the cabin while Henry and Pete go out for supplies, encounter Richard McCarthy, a disoriented and delirious stranger wandering near the lodge during a blizzard talking about lights in the sky. The victim of an alien abduction, McCarthy grows sicker and dies while sitting on the toilet. An extraterrestrial parasite eats its way out of his body and attacks the two men, killing Beaver. Jonesy inhales the spores of the strange reddish fungus that the stranger and his parasite have spread around the cabin, and an alien entity ("Mr. Gray") takes over his mind.
It becomes up to Henry—by now a quarantined prisoner of the Army—to convince the military to go after Jonesy/Mr. Gray before it is too late. Jonesy himself, now a prisoner in his own mind, tries to help. Both of them are convinced that their old friend Duddits may be the key to saving the world.