This Wednesday's all-new episode of "Arrow" will introduce Barry Allen aka The Flash.

According to an official synopsis, in the upcoming episode, which is called "The Scientist," Central City police scientist Barry Allen comes to town after a seemingly impossible robbery at Queen Consolidated's Applied Sciences Division. Citing a similar case back home, Barry, an assistant forensics investigator, offers to help Oliver and the team with the investigation. Oliver will have a hunch that there is more to Barry than meets the eye, however, as his mind tend to wander.

But, just in case you're itching for more info about The Flash and how he will mesh with Oliver, TV Line talked to executive producers Andrew Kreisberg and Greg Berlanti along with writer/DC Comics Chief Creative Officer Geoff Johns and Gustin to get more inside scoop.

Kreisberg compared Barry to Oliver stating, "He's the opposite of Oliver in a lot of ways - outgoing and funny, a little bit unsure of himself and smart." He continued making note of the physical contrast between the buffed up vigilante and Gustin's youthful alter ego.

"Arrow" producers described Barry as "as being a little bit younger," said Kreisberg, adding that because he lacks confidence and isn't as strong, Barry "needs the bolt of lightning to be a hero in a way [Oliver] doesn't need the bolt of lightning."

Johns added, "[Oliver] needs the heart, Barry has the heart. [Oliver] has the body, Barry needs the body."

TV Line also revealed that Alex Kingston is set to reprise her role as Dinah Lance in Episode 14.

"The Scientist" episode of "Arrow" is scheduled to air on Wednesday, Dec. 4 at 8 PM ET on The CW. Watch a preview below: