Part 1

A very powerful blizzard hits the fictional small town of Little Tall Island (also the setting of King's novel Dolores Claiborne) off the coast of Maine. This storm is so powerful that all access off the island is blocked, and no one is able to leave the island, until the storm is over. While trying to deal with the storm, the citizens of the town are visited by Andre Linoge (Colm Feore), a menacing stranger who apparently knows all of the townsfolk's darkest secrets (among which are abortion, adultery, growing marijuana, and gay-bashing). After having killed one of the town's residents, Linoge is jailed. Even though he is kept in jail by the town's trusted constable, Mike Anderson (Timothy Daly), Linoge is somehow able to force people to commit suicide or kill others from within his cell. Linoge constantly repeats "Give me what I want and I'll go away" through his victims as well as to his victims. Interestingly, although the adults are terrified of the stranger, all the children are drawn to him.

Part 2

In a dream, the townspeople see themselves walking into the sea two-by-two with the word Croatoan (a reference to the colony of Roanoke) carved on their heads. Eventually, Mike finds out that Linoge is an anagram of the demon Legion and agrees to organize the townspeople so they can hear his demands.

Part 3

What Linoge desires is an heir, one of the eight small children that he had incapacitated early on in the miniseries — someone to "carry on his work when he can no longer do it himself", although Linoge's life spans millennia, he is not immortal. Any of the eight children, he states, will suit him.