What's Past is Prologue



Critic Consensus: "What's Past is Prologue" takes viewers on a Flash-tastic journey back in time with a series of flashbacks that make for an eventful, charming, and commemorative 100th episode.

Episode Info

Barry and Team Flash come up with a plan to stop Cicada. The plan calls for Barry and Nora to travel back in time to gather some key necessities, however, and Barry hesitates, concerned about his daughter seeing certain parts of his life. Meanwhile, Sherloque takes his concerns about Nora to Iris, and Caitlin turns up a key asset in the fight against Cicada.


Grant Gustin
as Barry Allen/The Flash
Candice Patton
as Iris West
Danielle Panabaker
as Caitlin Snow
Carlos Valdes
as Cisco Ramon
Jesse L. Martin
as Det. Joe West
Tom Cavanagh
as Harrison Wells
Keiynan Lonsdale
as Wally West
View All

News & Interviews for What's Past is Prologue

What's Past is Prologue Videos

What's Past is Prologue Photos

Critic reviews for What's Past is Prologue

While the craft employed by the special-effects team to do this was skillfully handled and well-directed by Tom Cavanagh, the whole episode still feels like something of a missed opportunity.

December 7, 2018 | Full Review…

Absolutely nostalgic, incredible and just so well put together.

December 6, 2018 | Rating: 5/5 | Full Review…

Flash fans, we'll give you a moment to digest that timey-wimey craziness. OK, time's up.

December 6, 2018 | Full Review…

"What's Past is Prologue" celebrates the superhero series' landmark 100th episode with an installment that does its best to honor its past, while still moving this season's story forward. For the most part, it succeeds.

December 6, 2018 | Rating: 4/5 | Full Review…

What's Past Is Prologue did a terrific job of ending Cicada's threat...for now, while setting up a new mystery and the return of Thawne.

December 6, 2018 | Rating: 9.5/10 | Full Review…

The editing team did a fantastic job of blending old footage with new scenes, and for the most part, it really felt like Barry and Nora were peeking in on these key moments from Flash lore.

December 5, 2018 | Full Review…

Discussion Forum

Discuss The Flash on our TV talk forum!