The narrator was creeping on the old man while he was sleeping. This is a point leading up to the climax. One night the old mans eye was open and the narrator when crazy. In the story the narrator says "It was open-wide, wide open-and I grew furious as i gazed upon it."
The narrator lost it. "I dragged him to the floor, and pulled the bed off the heavy bed over him." A few minutes later this happens. "The old man was dead. I removed the bed and examined the corpse." This scene is important as it is the climax. It descirbes how he pulled him apart and hid the pieces under the bed and washed everything so there were no traces left.
The neighbor heard a screech and called the cops. They showed up but he was not worried. He was so confident in his skills that he invited them in and let them search. In the man's room they sat and placed his seat on top of the body. He thought he heard the old mans hear and confessed saying "I admit the deed!-tear up the planks!-here, here!-it is the beating of his hideous heart!"