Dreamcatcher

As children in a small Massachusetts town, four boys — Henry, Jonesy, Beaver, and Pete — saved a developmentally disabled boy named Duddits from a group of bullies. Duddits gave them a strange and lasting gift in return: a low-level telepathic connection between all five of them. Each grew up with mild psychic abilities. Duddits's are stronger.

Now adults, the four friends meet annually at their cabin in the Maine woods for a hunting trip. The weekend starts normally. Then a man appears stumbling out of the storm — disoriented, sick, bloated. Beaver and Jonesy take him in. The man dies in their bathroom. A worm-like alien parasite — a byrum, which the friends nickname "shit weasels" — bursts out of him and kills Beaver. Jonesy fights another byrum in the bathroom and is caught by it. Instead of being killed, his consciousness is overwritten. An alien intelligence calling itself Mr. Gray has taken his body. The real Jonesy is pushed into a small mental compartment of his own mind, where he watches in horror.

Mr. Gray begins driving south toward a Massachusetts reservoir, intending to seed the public water supply with byrum and trigger a global infection. Jonesy can still communicate telepathically with the others. Pete is killed by another byrum on the road.

A military quarantine has descended on the area. Col. Abraham Curtis runs it — a fanatic who believes the only solution is to exterminate everyone exposed, infected or not. His second-in-command, Owen Underhill, initially complies but is increasingly horrified by Curtis's willingness to massacre civilians.

Henry is captured by the military. Owen breaks ranks with Curtis and frees him. They flee together, intending to find Duddits — they believe he holds the key to stopping Mr. Gray.

Duddits is in a hospital, dying of leukemia. He has known this day was coming and insists on going with them. Curtis pursues, unhinged, intending to kill them all. He is killed in the chase.

Mr. Gray reaches the reservoir. Henry, Owen, and Duddits arrive in time. Duddits reveals what he has always been — an alien himself, or something close, sent or stranded on Earth long ago to act as a defender against exactly this. He confronts Mr. Gray directly. The two alien intelligences fight in psychic and physical form. Owen is killed. Duddits sacrifices himself to destroy Mr. Gray.