- For other uses of "Legacy", see Legacy.
- "I always wanted to be a hero, to use my extraordinary abilities to help people. That's why I came here: to meet my family, stop Cicada, help fix the Flash's legacy, and save him from disappearing in the future. I believed I could do the impossible, but I never imagined it would turn out like this. I'm glad it did. I wouldn't change anything about my time with you, my sweet parents, the most important people to me in the world. I wish I could be there to celebrate every new chapter, to witness every success. Just know... that no matter where I go in my life, you'll always be by my side. Because of you, I know I will never, ever, truly be alone, and I will feel your love and support like a warm hug comforting me, wishing me to be the best person I can be. Thank you for everything... for making me a hero and for loving me even if I wasn't perfect. Please remember that I love you both and I always will, no matter what the future brings."
- —Nora West-Allen's message to her parents
|Barry faces off with his oldest, and most formidable nemesis, Reverse-Flash.|
Having figured out, what the destruction of Cicada's dagger will do, Ralph stretches himself in between the dagger and the Mirror gun. He transforms into a cubic kind of form, and this allows Cicada to escape with the dagger. Others are baffled, why Ralph would stop them from destroying the dagger.
Barry and Nora check the precinct to see, if there are any clues about Cicada. Barry finds a small shard of wood, and seeing that the precinct has no wood around, it must have come from Cicada, maybe from where she is hiding.
In S.T.A.R. Labs, Team Flash is back at square one. Although they stopped Cicada from using the cryo atomizer, she is still a threat. Caitlin can't figure out how to turn Ralph back either. Meanwhile, in her hideout, Cicada comes up with a new plan to destroy meta-humans: use the time sphere to travel back to the moment the particle accelerator exploded and influence it with the meta-cure, so that the blast kills all those it transforms.
The wood shard is put into analysis, and everyone are still wondering, why Ralph stopped them. Sherloque then explains he solved the mystery; why does Eobard Thawne want the dagger destroyed? Because it is the very thing that keeps his meta-human powers suppressed in the future. Nora finally realizes that Thawne was using her from the beginning, that he only wants to help himself. But as long as Cicada has the dagger, no one is safe. The team finds themselves in making a hard choice: either destroy the dagger and free Thawne, or don't destroy it and let him get what's coming to him. Caitlin tells Cisco to go see Kamilla and tell her, who he is.
Cisco goes to Jitters, where Kamilla looks at her photos. Cisco reveals to her, that he works in S.T.A.R. Labs and how he created the meta-cure. Kamilla at first doesn't believe him, but sees he's serious. Cisco then uses his powers to demonstrate, and Kamilla realizes he is Vibe. Cisco apologizes and tries to leave, but Kamilla isn't angry; rather she understands, why Cisco didn't tell her right away. This boosts Cisco's spirit
Nora is in the speed lab, feeling down for not seeing Thawne's true agenda. She feels responsible about everything, but Barry comes and advises her to accept her mistakes and move forward. The analysis on the wood shard is finished, and it points to the same woods, where Dwyer nearly killed Cisco. Cicada must be in there. Nora comes in and says she came up with a plan to stop both Cicada and Thawne: use Cecile's empathy and MAD 2.0 to go into young Grace's mind to convince her to take the meta-cure. Caitlin still hasn't figured out how to help Ralph, until Sherloque figures out that Cisco's blasts can help. Cisco blasts Ralph, and he transforms back.
Barry, Nora, Ralph, Killer Frost and Cecile approach Cicada's cabin, and she sees the dagger glowing. She comes out to fight the heroes, but the team uses an extrapolarator to send her into Speed Prison in S.T.A.R. Labs in order to trap her, so that Nora can enter young Grace's mind unhindered. However, the prison can only hold her for a little time. Nora enters Grace's mind, and begins to convince her, how she will become a monster in the future that kills innocent people. Two Orlin Dwyers appear, the other trying to convincve her to become the monster while other tries to convince her to take the meta-cure. Cicada breaks free, just as young Grace decides not to become a killer and take the cure. As Nora leaves her mind, Grace's coma ends, and the cure is administered. Cicada appears, and attacks the team, knocking them all out, and the cure doesn't work. Sherloque figures out, that the shard inside Grace's head prevents the cure from working, as it is part of the dagger, so the dagger must be destroyed. Cisco sends the Mirror gun to Barry, just as Cicada is about to kill Nora. Barry shoots, and hit's the dagger, and as it is destroyed, the meta-cure on Grace starts working and Cicada starts to disappear, her existence erased.
In 2049, as the Iron Heights guards are preparing to execute Thawne, he breaks free; the dagger is no more. He kills the guards and electrocutes the warden, and then tries to flee, but time moves backwards, and Barry and Nora appear and this time all guards are saved. Thawne is impressed that Nora learned to turn back time. Barry then brings forth Thawne's plan: to have Nora aid Barry in destroying DeVoe's satellite, so that Cicada would be someone Team Flash could defeat (as they never caught the original Cicada, David Hersch). Thawne uses his ring to take his Reverse-Flash suit, and speedster chase takes place, in which Thawne uses a speed mirage to knock both Barry and Nora down. As he then tries to kill them both, a breach opens and Time Sphere appears, and crashes into Thawne. The remainder of Team Flash, Iris, Cisco, Killer Frost and Ralph, come from the breach to aid them. Thawne nods to everyone (indicating that Ralph should be dead, as he died in the original timeline). Thawne strikes, but with combined effort, Team Flash defeat him, and Nora slams him, and nearly kills him by tapping into Negative Speed Force, but Barry and Iris snap her out of it. Just then, Nora starts to disappear. Thawne says this was meant to happen, as the new timeline begins to set, in which she doesn't exist. Barry, in anguish, forces Thawne to tell him, how can they save her. Thawne says she needs to get into Negative Speed Force, as it is immune to timeline changes. He then disappears, telling Flash they will see each other in the next Crisis. Barry and Nora run into Negative Speed Force, but Nora says she can't do it, despite Barry's insistence. They come back, and Barry and Iris are griefstricken, as their daughter is about to be erased from existence. They insist Nora goes into the Negative Speed Force, but she refuses, as it would make her like Thawne, and she doesn't want that to be her legacy. She hugs her parents, as she is erased.
The team return to the present, and everyone are sad that Nora is gone. Joe says they will have to believe she'll come back. Joe's phone rings, and it says Captain Singh wants to see him, Barry and Cecile. Iris wants to be left alone, so Cisco, Caitlin and Ralph leave her, and Sherloque returns to his Earth. All that is left of Nora is her diary. Iris takes it and begins to cry.
In CCPD, Singh reveals that Grace is to be given into custody and congratulates Joe, Barry and Cecile for protecting the city, and he reveals the mayor has offered him the position as the chief of police, and he wants Joe to be his successor as the captain. He also reveals that he knows Barry is the Flash. In S.T.A.R. Labs, Cisco is pondering, about what Thawne said about him, and he doesn't want that. He asks Caitlin to give him the meta-cure and stop being Vibe. Caitlin is saddened about it, but gives it to him. Cisco reveals he left something for Caitlin in his workshop.
As Barry returns, he finds Iris in the Time Vault. They contemplate about their time with Nora, and see that they were good parents. Nora's diary is still intact, as the time language in it never fades. Barry discovers something else in it: a memory drive for Gideon. They plug it inside: it's a video Nora made in case something went wrong in their efforts. In it she reveals that despite that, she got the chance to become a hero and loves her parents unconditionally. As Nora speaks, a montage about each member of Team Flash is shown: Joe takes the police captain's position with Cecile at his side, Cisco walks with Kamilla, Caitlin finds Cisco's present in his workshop, Ralph is in his office and takes a new case and Sherloque is in Jitters on his Earth, as the door opens telekinetically. Barry and Iris watch Nora's video with both joy and sadness.
Later, Gideon detects a time flux. The future news article about Flash vanishing in Crisis appears, and it's date starts to change. The counter stops: the time of the Crisis has moved from 2024 to 2019!
- Grant Gustin as Barry Allen/The Flash
- Candice Patton as Iris West-Allen
- Danielle Panabaker as Dr. Caitlin Snow/Killer Frost
- Carlos Valdes as Cisco Ramon/Vibe
- Hartley Sawyer as Ralph Dibny/Elongated Man
- Danielle Nicolet as District Attorney Cecile Horton
- Jessica Parker Kennedy as Nora West-Allen/XS
- Chris Klein as Orlin Dwyer
- Tom Cavanagh as Harrison Sherloque Wells and Professor Eobard Thawne/Reverse-Flash
- Jesse L. Martin as Detective Joe West
- Patrick Sabongui as Captain David Singh
- Sarah Carter as older Grace Gibbons/Cicada
- Victoria Park as Kamilla Hwang
- This marks the last appearance of Jessica Parker Kennedy and Chris Klein as series regulars.
- This is the only season finale in the 2018-19 season of in shared multiverse to not feature Mar Novu/The Monitor.
- However, like this season's finales of the respective seasons of , and , this episode still prepared for the ; Thawne says to Barry "see you at our next Crisis", referencing as he knows that in the new timeline (created by Team Flash destroying Cicada's dagger), the "Crisis" will now happen in 2019 instead of 2024, as shown at the end of the episode by the date on the newspaper in the Time Vault changing from 2024 to 2019.
- Despite the threat, Thawne never appeared in that crisis. Instead, he resurfaces afterwards during Nash's struggle with all the Wells doppelgängers inhabiting his body, which Nash refers to as "Crisis of Infinite Wells" in "".
- This is the first season finale to end with a post ending title scene.
- Barry gives Nora the same speech Jay gave him after he stopped him from trying to fix Flashpoint in "". This is the second time he tells her this, the first time being "".
- Thawne notes that Ralph should be dead, referencing to the events of the Season 1 episode "", where he revealed that Ralph was one of the people who died from the particle accelerator, for which he was until Barry created Flashpoint.
- Nora being erased from existence was alluded in the Season 5 premiere, "", when Barry says that she could possibly "Marty McFly herself out of existence", referring to the protagonist of the 1985 film Back to the Future, who accidentally interferes with his parents' first meeting whilst traveling back in time, nearly erasing himself from existence.
- The way Nora disintegrates when being erased from existence is similar to how Eobard Thawne and Savitar disintegrated in the episodes "" and "" when they were erased from existence, and how Eobard was killed by Black Flash in the episode "".
- Team Flash arriving in the Time Sphere through a wormhole and smashing into Eobard can be considered a reversal of what happened in the season 1 finale "", in which Barry arrived through a wormhole and smashed into the Time Sphere Eobard was in.
- Eobard mentions the time he murdered Cisco in an erased timeline, referring to the season 1 episode "".
- He even mentions that Nora was like a daughter, in a similar way that he spoke about Cisco in that episode being like a son to him, saying that she taught him what it was like to have a daughter.
- Cisco mentions the thought of playing Gaga to wake Ralph up which refers to when he and Caitlin played the Lady Gaga song "Poker Face" to wake Barry up in "".
- At the end of the episode, Ralph opens a case file marked with the name Dearbon. This is a reference to his wife in the comics, Sue Dibny, whose maiden name was Dearbon.
- Thawne mentions that " this is the second time that I've been stuck somewhere for 15 years", a reference to Season 1 when he was stuck in the 21st century from 2000 to 2015.
- Eobard splits himself in two, a reference to what Godspeed does in the comics as his signature move saying "God has the ability to be in all places at the same time", but in doing so his aspects become much weaker which is why Thawne pulls himself back.
- Future Grace's hideout is located in the woods where Orlin tried to kill Cisco in "".
- After Cicada's dagger disappears in 2049, and Eobard escapes from containment at Iron Heights, a silhouette of his suit, made up of the dagger's outline and his yellow prison jump suit can be seen.
- The way Thawne guessed that Nora and Barry are present before turning around after escaping is very similar to the way he did in "" when he sensed Barry and Nora's presence.
- When Thawne finished killing the guards, his hair reverted to black. This is caused by his disguise as Harrison Wells who had black hair. During his imprisonments, his power of disguise faded and his hair became brown like his original appearance. With the powers fully restored when he escaped, his disguise were fully working again.
- This marks the third time that Barry has lost a loved one; his daughter. The first was his mother who was killed by Thawne fourteen years prior to the "" and the second was his father, who was killed by Zoom in "".
- Furthermore, in what is now an erased timeline, Barry also lost Iris after she'd been murdered by Savitar.
- In all of these instances, an evil speedster had been directly responsible for the death of a person Barry loves.
- Team Flash's actions of destroying Cicada's dagger not only brought the Crisis earlier, but also Oliver Queen's presumed death.
- Eobard Thawne getting Nora to help Team Flash to destroy Cicada's dagger may be an example of a time loop. He says that Nora and Barry helped him escape prison. He then explains that when they traveled to the Time Vault (when they went back in time in "" and made him fix the damaged Speed Force transmitter vial), he asked what it's for. Barry said that it's to drain dark matter. Eobard then wanted to know whose dark matter they're trying to drain; Barry argued that it isn't Thawne's business, but Nora then blurted out that they're trying to stop Cicada. Thawne then remembered this years later when he ended up in prison with the dagger strapped to his chest, dampening his powers. He goes on to explain that he then knew that he had to get Nora to trust him so that a different Cicada would be created; one they could stop (since Team Flash never managed to defeat Cicada in the original timeline), which is the reason Thawne sent Nora back in time in the first place; to ensure that the dagger would be destroyed, making it possible for him to escape his confinement to avoid execution.
- In a deleted scene, Nora mentions the Flash Museum's chapter on Zoom, saying that it was called "". This was the title of the season 2 finale; and season 2 of the series is when those events took place.
- As of this episode, the newspaper changed drastically. The year is shown to be 2019 instead of 2024. Hawkgirl is not mentioned anymore, instead it mentions White Canary, Supergirl, and Batwoman. Joe West is referred to as Central City Police Captain, instead of CCPD Chief, corresponding to the events of this episode. Moreover, Starling City is changed to Star City.
- Because Barry destroyed Cicada's dagger in 2019, this should mean that it's never used to dampen Eobard's powers while he's in prison. This means, when he ends up getting put in Iron Heights on death row in the new timeline (in which the dagger had been destroyed in 2019), the prison staff should just take different measures to dampen his powers while he sits on death row, allowing him to be executed without any problems.
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