Plot summary
In June 1971, Vietnam veteran William Davis is discharged from the military; his wartime experiences have left him "empty", with his "emotions scrubbed". After staying with his mother in Skowhegan, Maine, Davis relocates to Portland and finds work as a stenographer for Temp-O. The following year, Davis responds to a job advertisement posted by Elgin, a self-described gentleman scientist in Castle Rock. Elgin hires Davis as an assistant for his experiments, which aim to "go under" the wall of sleep.
Elgin and Davis begin their experiments, which entail administering the hypnotic drug Flurazepam to a human test subject who is instructed to study a picture of a red house with a green door in a forest. The subject is then instructed to dream of the house, and then to enter the house and attempt to lift up the living room floor and see what is beneath. Elgin and Davis watch the subject through a one-way mirror, with Davis transcribing the subject's remarks.
Davis witnesses the teeth of the first subject, Althea Gibson, grow larger. After awakening, she states that upon lifting the living room floor in her dream, she saw "darkness" and smelled a "stench". Elgin explains to Davis that the drug rendered Althea suggestible, enabling her to access "the reality beneath the dream". Elgin theorizes that dreams are a barrier between humans and the "matrix of existence", and that his experiments will enable him to look past this barrier.
The second and third experiments are unsuccessful, while the fourth test subject does not appear. The fifth subject, Hiram Gaskill, writes "the moon is full of demons" in Vietnamese on a writing pad while asleep. Davis grows apprehensive and advises Elgin to terminate the experiment; Elgin refuses. Davis himself ultimately decides to remain Elgin's assistant, seeing his curiosity in the experiment as a sign that his humanity remains. The sixth subject, Annette Crosby, awakens screaming, having dreamed of opening the green door to encounter a disembodied voice that uttered a word resembling "tantullah" or "tamtusha".
The final test subject is Burt Devereaux. During the experiment, Devereaux's eyeballs turn black, swell and split, emitting black filaments. He is left catatonic. Davis drives Devereaux to a rest area off Route 119 and abandons him there in his car, then hitchhikes back to Castle Rock. When he arrives back at Elgin's house, he finds Elgin in the test room with his head swathed in the filaments. As Davis watches, the filaments spell out his name on the one-way mirror. Davis turns on the house's gas stove and uses his lighter to ignite an explosion that destroys the house.
Davis returns to Temp-O. When he is interviewed by the police, he maintains that he left his job some time before the explosion. In September 1972, Davis relocates to Nebraska, where he begins working on a farm. Davis dreams of standing outside the red house with the green door; he knows that one day he will open the door and enter the house, where "there will be no mercy".
