: To rescue Joe, Barry returns to the sewers wearing a "magnetic resonance" headpiece designed by Cisco and Caitlin to block Grodd's telepathy. During the fight, Grodd breaks the device and attacks Barry’s mind. Iris uses the S.T.A.R. Labs comms to give Barry a motivational speech, helping him break Grodd's control. Barry eventually defeats Grodd by luring him into the path of an oncoming train.

: Iris West finally confronts Barry after discovering his secret identity as The Flash. She is deeply hurt that both Barry and her father, Joe West, kept the truth from her to "protect" her.

: Meanwhile, Eobard Thawne taunts the captive Eddie, telling him he is the most "unremarkable" of the Thawne family and showing him a future newspaper revealing that Iris eventually marries Barry, not him.

: Wells completes a device he calls "the key" and inserts it into a hidden chamber in the pipeline, which lights up a long tunnel, presumably his ticket back to his own time. Key Character Moments

The Flash Season 1, Episode 21, titled , originally aired on May 5, 2015. This episode centers on the introduction of the telepathic gorilla, Grodd, whom Dr. Harrison Wells (Eobard Thawne) unleashes as a distraction while he continues his own plans. Plot Summary

The episode begins with Central City Police dealing with the disappearance of Eddie Thawne, who has been kidnapped by Eobard Thawne.