Barry Allen (Grant Gustin) finally learns why Harrison Wells (Tom Cavanagh) killed his mother when he was just a boy in the extended trailer for The Flash season finale, "Fast Enough", airing Tuesday, May 19 at 8 PM ET on The CW. Harrison reveals that he killed Barry's mother because he hates him, although we'll have to tune into the finale to learn exactly what the root of Harrison/Eobard Thawne's hatred for Barry truly is. Now Barry has the opportunity to go back in time and save his mother.

The trailer also shows Caitlin Snow (Danielle Panabaker) seemingly getting married to her fiancee Ronnie Raymond (Robbie Amell), as Joe (Jesse L. Martin) tells Barry that he has no choice but to change the past, although there may be some slight complications. During his trip back to the past, something goes wrong, as Barry could possibly be erased from existence as he tries to save his mother from being killed by Reverse Flash. As you can see in the trailer below, it may all be worth the trouble after all.

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This episode also features both Dr. Martin Stein (guest star Victor Garber) and Ronnie Raymond (guest star Robbie Amell) as Firestorm, who return to help the S.T.A.R. Labs team with this final fight. How will this explosive first season of The Flash come to an end? Check out the trailer below, and stay tuned for more clips and footage as we get closer to the season finale on Tuesday, May 19.