The narrator loses her mind following months of confinement in the rented mansion. She tears down the wallpaper and goes completely insane, as her husband John faints at the sight of it.
Detailed answer:
Toward the end of The Yellow Wallpaper, the narrator’s diary entries change their style and become more concise. She begins to keep secrets from her husband, his sister, and the reader. The narrator’s obsession with the yellow wallpaper in her nursery grows stronger. According to her diary, she begins to smell the wallpaper all around the mansion. At some point, the narrator even considers burning the place down because it causes her too much suffering.
Nevertheless, Jane rejects this idea. She decides to resolve the mysteries of the house and the yellow wallpaper. Jane finds Jennie examining the wall and suspects to have a rival. So, Jane is determined to act quickly, fueled by her obsession. She believes that a woman is trapped in the yellow pattern of the wallpaper and decides to set her free.
The narration reaches its climax when the narrator tears down the wallpaper. She thinks she has released the woman and goes completely insane. The narrator now associates herself with the woman from the wall and refuses to leave the room. As John returns home, he finds his wife crawling on the floor and faints. But the narrator keeps running around her husband’s body.