New York Times–bestselling novelist David R. George III takes a look back at one of the most popular Star Trek episodes ever produced, "The City on the Edge of Forever." The piece considers the episode's initial broadcast and reception, explores the resulting feud between writer Harlan Ellison and Trek creator Gene Roddenberry, looks at the central guest character of Edith Keeler, surveys time travel within and without the various Trek shows, and studies the moral questions raised in the story. Heavily sourced and annotated, Depths of Forever is a must-read for fans of The Original Series.