What is the main idea of the book dreamcatcher by Stephen King?

A group of friends since childhood befriend a mentally handicapped boy when they are young. Turns out, he has special telepathic powers, and it spreads to them, making them special.

Much later, when they are grown-ups, we discover that aliens are invading the planet, trying to infect us with a virus that will create more aliens. Due to their special abilities (telepathy, clairvoyance, etc.) the friends and their retarded friend find out what is happening to Earth, and put a stop to it, saving the human race.