Insomnia is the 34th book published by Stephen King; it was his 29th novel, and the 24th written under his own name. It is related to King's Dark Tower series. Like Rose Madder, the novel draws heavily from Greek mythology for its metaphysical elements. It is set in the town of Derry, Maine.
After his wife's death, Ralph Roberts begins to suffer from insomnia. He comes aware that something is wrong with his neighbor, Ed Deepneau, after several disturbing incidents, including the beating of his wife, Helen. Ralph begins questioning his sanity after he starts seeing auras around people and "little bald doctors". Meanwhile, Ed has joined forces with a pro-life group to protest a speech given in Derry by noted-pro-choice activist, Susan Day.
Ralph discovers that a similar thing has been happening to his sweetheart, Lois Chasse. Together, they confront the little bald doctors. They name the two that they talk to Clotho and Lachesis and the other one, Atropos. Clotho and Lachesis want to preserve the natural order of death while Atropos brings chaos. They reveal that Atropos is serving as an agent of the Crimson King to bring about the death of everyone who attends Susan Day's speech through the person of Ed Deepneau.
Ralph and Lois venture into Atropos' lair in order to thwart his part of the Crimson King's plan. They are partially successful, but Atropos promises revenge. Ralph uses his powers to enter Ed's plane that he intends to crash into the Derry Civic Center. Ralph intends to defuse Ed's bomb, but the Crimson King himself arrives to prevent this. Ralph stands tall in the face of the King and is able to defuse it. Lois rescues him from the plane. It is revealed that only one person in the Civic Center was of cosmic significance, Patrick Danville.
Ralph and Lois get married and live together for many years. Ralph gives his life to save Helen's daughter, Natalie, from Atropos.