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

In season 2, episode 8, 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.

In the meantime, Oliver will notice that Felicity takes a liking to Barry and disapproves. Sin also asks Roy for help when a friend of hers goes missing. In response, Roy is when Thea not only encourages him to help, but subsequently joins the search. Unfortunately, Sin's friend is connected to Brother Blood and their search results with one of them getting seriously injured.

The official synopsis for the episode states that, "Police scientist Barry Allen travels to Starling City to investigate a seemingly impossible robbery from Queen Consolidated's Applied Science Division, and Felicity takes a liking to him... much to Oliver's dismay. Meanwhile, Sin asks Roy for help tracking down a missing friend, and Thea joins her boyfriend in the hunt, only for one of them to be injured," reports TV.com.

According to TV Line, The Flash will be played by "Glee's" Grant Gustin and will also return in Episode 9, "Three Ghosts."

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