Daniel Quinn is the protagonist of the trilogy’s first story, City of Glass. Quinn is haunted by a tragic past. He has lost his wife and son, and chooses to live a secluded and solitary life. He is 35 years old. He used to be an “ambitious” writer of poetry, plays, essays, and translations, but now he writes mystery novels. Quinn spends much of his time reading, admiring art, watching baseball, going to the movies, and “wandering aimlessly” around New York to escape his inner thoughts. Quinn associates himself with different names. He publishes his books under the pseudonym William Wilson and his real name is unknown to the public. Quinn detaches himself from his work and “[does] not feel responsible for it” (4). As a person, Quinn exists only for himself; his William Wilson persona leads “an independent life” (4). Quinn feels connected to the protagonist of his detective novels, Max Work. Max Work is his fictional private-detective character and his “comrade in solitude” (6). As a writer, he identifies himself with an imaginary character.

Quinn explicitly represents the role of the writer as a detective when the Stillman case thrusts him into the world of private investigation.