Cisco's (Carlos Valdes) curiosity may end up killing him in the upcoming episode of the hit The CW series "The Flash."

In "Reverse Flash Returns," the synopsis reveals that Barry (Grant Gustin) will not believe it when the tech wiz tells him he is getting a vibe of Eobard Thawne aka Reverse Flash (guest star Matthew Letscher). Team Flash has doubts as well, since it is a known fact that he died during Eddie's (Rick Cosnett) suicide sacrifice back in season 1. But if the villain indeed is dead, why does Cisco have a nagging feeling that he is in Central City?

In the promo, Cisco can be seen entering the dimly lit laboratory, while calling Barry's name. Apparently, his suspicions make him jumpy, as he screams when Eobard's apparition suddenly pops up. Cisco is right and Christina (guest star Amanda Pays) can confirm it. The Reverse Flash has returned and he wastes no time in making his presence known, launching an attack at Mercury Labs. Barry has his proof that the speedster is in the city once more.

Dr. Wells (Tom Cavanaugh) posits an idea on how Eobard is able to return from the dead. In the teaser, he is saying that his bizarre reappearance has something to do with time travel.

"This is how he learns about you, all of you. This is his origin story and there is nothing you can do about it," the scientist said.

Apparently, this Eobard that Barry will be facing is not the Dr. Wells from Earth 1. He is actually the original, strong villain who has yet to lose his speed. The time travel makes it possible for him to find Barry and kill him to prevent the event in the future where Barry defeats him. It looks like Barry has to take down this foe first before focusing on how to stop Zoom (Tony Todd). But as the promo suggests, he will have a hard time doing it.

Also in episode 11, Iris (Candice Patton) will finally get her opportunity to be close to her brother Wally (Keiynan Lonsdale), thanks to Francine (guest star Vanessa A. Williams).

"The Flash" airs Tuesdays at 8 p.m. EST on The CW.