In the episode, titled "King Shark," Diggle (David Ramsey) and Lila (Audrey Marie Anderson) take a trip to Central City, but it's not a carefree vacation. They're there to warn Barry Allen and Team Flash of the return of one of the fiercest metahumans of all, King Shark.
When King Shark escapes from an A.R.G.U.S. holding tank, Lila (guest star Audrey Marie Anderson) and Diggle (David Ramsey) travel to Central City to warn The Flash (Grant Gustin). King Shark shows up at the West house and attacks Joe (Jesse L. Martin), Iris (Candice Patton), Wally (Keiynan Lonsdale) and Barry. Hanelle Culpepper directed the episode written by Benjamin Raab & Deric A. Hughes (#215)
"The Flash" airs Tuesdays at 8/7c on The CW.