The Flash Season 3 Episode 21
Cause and Effect
Barry takes drastic measures to stop Savitar. Meanwhile, H.R. continues to push Tracy Brand to design the trap for Savitar and Killer Frost returns with an interesting proposal.
Guest Stars
Danielle Nicolet
Cecile Horton
Richard Zeman
Lucius Coolidge / Heat Monger
Liam Hughes
Young Barry
Sasha Rojen
Young Iris
Tobin Bell
Savitar (voice) (uncredited)