Blue is a private detective in New York, working at Brown’s agency. Brown has been Blue’s teacher in the profession and is now retired. The story begins when White visits Blue and hires him to watch a man named Black; he doesn’t say why. He has rented a small apartment for Blue across the street from Black’s apartment. White asks Blue for a weekly written report.

The story starts in 1947 and continues for years. Blue says goodbye to his companion, “the future Mrs Blue” (138), and settles in the small apartment at Orange Street. He starts watching Black from the window, seeing the man writing at his desk. Blue records his observations in a notebook. Later, Blue watches Black having dinner and reading a book, Thoreau’s Walden. Days pass and Blue becomes disillusioned. Black only reads, writes, and occasionally walks around the block. Blue thinks the only way to understand is to see into Black’s mind. To occupy himself, Blue reads magazines, particularly True Detective.

Blue struggles to adjust to this new reality. Accustomed to observing “the surface of things” (145), he realizes he never considered his inner world. To make sense of the case, Blue starts inventing stories about Black and White’s relationship.