The narrator has already decided to kill the old man with whom he shares a home. He will wait until the old man is asleep and, "about midnight," slowly enter his bedroom. The narrator works at a painstakingly slow pace, "very, very slowly" unlatching and opening the door before poking his head inside.
It took me an hour to place my whole head within the opening so far that I could see him as he lay upon his bed.
Then, once inside, the narrator watched over the old man, allowing only "a single thin ray" of light from a covered lantern to shine upon the sleeping man. The narrator repeats this ritual each night for a week, but it is not deliberate: The narrator refuses to kill the old man while he is asleep. The old man must be awake so the narrator can see that his eye,
... the eye of a vulture... his Evil Eye...
is open. Only then will the narrator strike out. Finally, on the eighth night, the murderer finds the old man's eye open--but only after awakening him when his "thumb slipped upon the tin fastening" of the lantern. After allowing the old man to wait in "mortal terror," the narrator finally screws up the courage to make his attack, throwing the old man to the floor and placing the bed over him. When the old man was "stone dead" and "his eye would trouble me no more," the narrator calmly dismembered the body.