'The Flash' Faces Familiar Foes in 100th Episode Preview

The CW has released a new preview for "What's Past is Prologue", the eighth episode of The Flash's fifth season, and the series' 100th episode overall.

The milestone episode will see Barry (Grant Gustin) and Nora (Jessica Parker Kennedy) traveling back in time, as a way to "gather some key necessities" to stop Orlin Dwyer/Cicada (Chris Klein). Even though Barry is well aware that he's not supposed to travel back in time anymore, it sounds like his and Nora's quest will be pretty dire, and will conveniently provide a way for The Flash's to look back at the past 100 episodes, similarly to how Arrow used an alien dream world for its 100th episode in the "Invasion!" crossover.

While it's unclear exactly what Barry and Nora will find when they travel back in time, it looks like they will cross paths with several of the show's past speedsters. The former voice of Zoom, Tony Todd, previously confirmed he has a role in the episode, and fans can also spot Eobard Thawne and Savitar in the promo as well.

The episode will also serve as The Flash's last installment before this year's "Elseworlds" crossover, so fans will definitely be curious to see exactly how things wrap up.

You can check out the synopsis for "What's Past is Prologue" below!

"TOM CAVANAGH DIRECTS THE 100TH EPISODE — 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.

Tom Cavanagh directed the episode written by Todd Helbing & Lauren Certo."

The Flash airs Tuesdays at 8/7c on The CW. "What's Past is Prologue" will air on December 4th.