Pariah (Tom Cavanagh) enlists Black Lightning (guest star Cress Williams) to help stop the Anti-Monitor (guest star LaMonica Garrett) after Flash-90 (guest star John Wesley Shipp) shares what he learned from his battle in ‘Elseworlds.’ With the help of Black Lightning, Barry (Grant Gustin), Cisco (Carlos Valdes) and Killer Frost (Danielle Panabaker) come up with a plan that could save them all. Meanwhile, Iris (Candice Patton) has a heart-to-heart with Ryan Choi (guest star Osric Chau), while Oliver (guest star Stephen Amell) and Diggle (guest star David Ramsey) return to an old familiar stomping ground.