Crisis on Infinite Earths: Part Two (II) - S1.E9

The group uses Ray's invention to track new recruits to help save the universe. The Monitor sends Iris, Clark and Lois in search of a mysterious Kryptonian, while Kate and Kara head out to find Bruce Wayne. In addition, Mia challenges Sara, Rory discovers a hidden talent, and Lex Luthor returns.

This crossover begins on Supergirl S5E09, and continues on The Flash S6E09, Arrow S8E08, and Legends of Tomorrow S05E01.