The City of Mirrors is a 2016 horror novel by Justin Cronin and is the final novel in The Passage trilogy, following the novel The Twelve. The City of Mirrors picks up where The Twelve left off, following the destruction of the Twelve and their viral followers, and explores the background of Subject Zero, the first human to be changed in the early 21st century. In doing so, it delves into lengthy flashbacks, and also jumps 900 years into the future to reveal humanity's fate.