A mysterious figure known as gives the "Book of Destiny" to a radical psychiatrist, Dr. John Deegan. Deegan uses it to rewrite reality, causing Barry and Oliver to swap identities.

This episode originally aired on , and serves as the explosive kickoff to the 2018 Arrowverse crossover event. ⚡ Episode Overview Title: Elseworlds, Part 1 Season/Episode: Season 5, Episode 9 (Episode 101 overall)

wakes up as The Flash, living Barry's life with Iris West-Allen. 2. The Struggle for Truth