‘The Flash’ Season 3 Episode 21 Promo, Spoilers: Barry Loses His Memories To Stop Savitar

In "The Flash" Season 3 Episode 21 titled "Cause and Effect," Team Flash is desperate to defeat Savitar. Cisco has a plan but it involves preventing Barry Allen from creating memories, which Barry agrees but he ends up losing his memories.

According to the synopsis from Cartermatt, in "The Flash" Season 3 Episode 21, Barry Allen (Grant Gustin) takes drastic measures to defeat Savitar. This includes subjecting himself to an experiment that has an adverse effect--it wiped his memories clean.

The CW has released a promo for "The Flash "Season 3 Episode 21, which sees Team Flash brainstorming on ways to defeat Savitar. Cisco suggests that Barry stops making memories to prevent the villain from remembering anything that happens in the present. This way Savitar would not remember everything that present Barry does.

Barry agrees to Cisco's plan and goes through the experiment. However, the team is not prepared for the adverse outcome. The promo for "The Flash" Season 3 Episode 21 shows Barry forgetting where he is. He wakes up thinking he is in a dentist's office, even though he is in S.T.A.R. Labs. He seems to have forgotten his friends too. Cisco explains that Barry's memory loss may be due to a slight miscalculation.

Meanwhile, H.R. Wells (Tom Cavanaugh) continues to push the scientist Tracy Brand to make the trap for Savitar. It seems Tracy is now determined to help Team Flash after she saw Savitar herself in Episode 20. Killer Frost, on the other hand, offers the team an interesting proposal in "The Flash" Season 3 Episode 21.

"The Flash" Season 3 Episode 21 takes off after Barry learned the identity of Savitar. It turned out that the villain is future Flash or future Barry Allen. According to Entertainment Weekly, the scarred-face Barry is the one who lost Iris and never fully recovered from her death

Will Barry regain his memories and defeat Savitar in "The Flash" Season 3 Episode 21? Will the team finally get their hands on the trap? Find out when "Cause and Effect" airs May 9 on The CW.