It was been announced that Katie will be making her guest appearance on The Flash on episode 19! Bellow, you have a synopsis of the episode. As a fan of both shows, i can’t wait to see this episode!
JOE AND CISCO TRAVEL TO STARLING CITY FOR ANSWERS ABOUT DR. WELLS — Joe (Jesse L. Martin) and Cisco (Carlos Valdes) head to Starling City to continue their investigation of Dr. Wells (Tom Cavanagh). While in town, the duo enlists the help of Captain Lance (guest star Paul Blackthorne), and Cisco meets the Black Canary (guest star Katie Cassidy), who asks him for a favor. Meanwhile, back in Central City, Barry (Grant Gustin) races to catch a meta-human named Hannibal Bates (guest star Martin Novotny) who can transform himself into every person he touches – which includes Eddie (Rick Cosnett), Iris (Candice Patton), Caitlin (Danielle Panabaker) and even The Flash. Wendey Stanzler directed the episode written by Ray Utarnachitt & Cortney Norris (#119). Original airdate 4/21/2015.