About The Flash (2014) 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, Grant Gustin, Richard Zeman, Liam Hughes, Sasha Rojen, Tobin Bell, Anne Dudek, Andre Tricoteux, Ken Camroux-Taylor,