Who is Harrison Wells?

"Who have we been working for this whole time? Dr. McGee said that after the accident, Wells became a completely different person. It's because he is a different person."

- Team Flash learning "Wells" was never Wells and that he's someone completely different

"Who is Harrison Wells?" is the nineteenth episode of the first season of The Flash and the nineteenth episode overall. It aired on April 21, 2015.

Synopsis
Joe and Cisco head to Starling City to continue their investigation of Dr. Wells. While in town, the duo enlists the help of Captain Lance and Cisco meets the Black Canary, who asks him for a favor. Meanwhile, back in Central City, Barry races to catch a meta-human named Hannibal Bates who can transform himself into every person he touches – which includes Eddie, Iris, Caitlin and even The Flash.

Production
Preparation began February 2, 2015 and ran until February 11, 2015. Shooting began February 12, 2015 and ran until February 24, 2015.

Trivia

 * Coast City is briefly seen for the first time in Arrow/The Flash. Previously the city had only been mentioned.
 * This episode marks the only appearance of Laurel Lance on The Flash.