Supergirl 4x22 "The Quest for Peace" Season 4 Episode 22 Promo Trailer (Season Finale) - LEX LUTHOR RETURNS — Lex Luthor (guest star Jon Cryer) descends upon Washington, DC and summons Lena (Katie McGrath) and Lillian Luthor (guest star Brenda Strong) to the White House. Supergirl (Melissa Benoist) realizes she has one last chance to stop Lex and turns to the power of the press to help her. Jesse Warn directed the episode with story by Robert Rovner & Jessica Queller and teleplay by Rob Wright & Derek Simon (#422). Original airdate 5/19/2019.