The Flash 100th-Episode Promo Brings Back Reverse-Flash

Harrison Wells in The Flash Season One

"Things just got a lot more complicated."

Ever since the start of Season 5 of The CW superhero series The Flash, Barry Allen and his friends have been dealing with the threat of the newest supervillain on the scene, Cicada. With the villain's origin now revealed with last night's episode, it's time for the Scarlet Speedster to try and defeat his opponent -- by time-traveling back to the past.

But while Barry Allen has traveled back to the past before, this time will be quite different. In order to celebrate the 100th episode of the series, "What's Past is Prologue" will see Barry travel back through the entire history of the series.

The first promo trailer of the episode have given us a glimpse of what we can expect from Barry's trip through time, and it looks like it will bring back some familiar faces. Not only will the Scarlet Speedster tackle with Hunter Zolomon's Zoom once again, he will also come face-to-face with his greatest enemy, the Reverse-Flash -- back when he wore the face of Harrison Wells, in Season 1.

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The return is quite noteworthy, given that while Tom Cavanaugh has played many different versions of Harrison Wells throughout the series, his take on Eobard Thawne, aka the Reverse-Flash, has always been the clear fan-favorite.

The promo ends with Barry and his daughter Nora finding themselves in Well's famous time vault, with the supervillain apparently aware of their presence. Given that he himself is a time-traveler, it's clear that he understands the potential ramifications of playing with time like this. Thanks to the reality-warping events of "Flashpoint," we have already seen what Barry's trips to the past can bring. Will reality be altered once again?

Here is the full synopsis for The Flash's 100th episode, "What's Past is Prologue," which will air next Tuesday:

"In the 100th episode, Barry (Grant Gustin) and Team Flash come up with a plan to stop Cicada (Chris Klein). However, the plan calls for Barry and Nora (Jessica Parker Kennedy) to travel back in time to gather some key necessities. However, Barry hesitates, concerned about his daughter seeing certain parts of his life.

Meanwhile, Sherloque (Tom Cavanagh) takes his concerns about Nora to Iris (Candice Patton), and Caitlin (Danielle Panabaker) turns up a key asset in the fight against Cicada."

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Airing Tuesday nights on The CW, The Flash stars Grant Gustin, Candice Patton, Carlos Valdes, Danielle Panabaker, Tom Cavanaugh, Jesse L. Martin, Danielle Nicolet, Hartley Sawyer and Jessica Parker Kennedy.

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