Dr. Anna Fox is the narrator of The Woman in the Window, as well as the woman to whom the title refers. Wracked by guilt, regret, and trauma, Anna is agoraphobic; she watches the world outside her New York City brownstone from the comfort of her own home. Anna also plays chess, studies French, watches old movies, and connects with fellow agoraphobes in an online community to pass the time. Anna is an insightful person, and she is clever and self-aware; she is also, however, unable to move on from a traumatic car accident that killed her daughter and husband, and she complicates the intended effects of her psychotropic medications with regular alcohol abuse.

When Anna witnesses an act of murderous domestic violence from her home, she believes she has watched a murder take place, but when others in her life doubt her, like the detectives who get involved and the neighbors directly affected by the crime, she begins to doubt herself. Her narration is unreliable to the reader, to the other characters in the novel, and even to herself; because Anna is a child psychologist, she understands the inner workings of the mind, yet her own pain, her guilt, and her inability to overcome the loss of her family obstructs her own understanding of herself and her situation.