“The Once and Future Flash” is episode nineteen of season three of The Flash.
It’s snowing and Barry is in the apartment with iris. He says he’s figured it out. The article in the time vault shows that, in 2024, Barry is still in Central City and there’s no mention of Savitar. So, Barry must have trapped him in the Speed Force. If Future Barry trapped Savitar, he must have figured out who he was. Iris isn’t paying attention. She’s thinking about the future, and her father. If Iris dies, she needs Barry to be there for Joe. She needs him to promise. Despite insisting that he’s going to save Iris, Barry eventually does.
Then he gets an alert from S.T.A.R. Labs. In the previous episode, “Abra Kadabra”, although Barry doesn’t know this yet, Caitlin died from the injuries she suffered during Abra Kadabra’s escape. Julian refused to accept this, and ripped off her necklace. Which caused Caitlin’s powers to activate, curing her. And turning her into Killer Frost. Could Caitlin be the real one who was going to suffer a fate worse than death, given that she would rather have died than become Killer Frost?
Killer Frost is currently blasting things and H.R. and Cisco flee. Julian tries to get Caitlin’s necklace, but she destroys it. He tells her he does care for her, and she asks him to show her. Going to kiss Julian. Which has been seen to be fatal for anyone but Firestorm. However, Cisco blasts Killer Frost and the three run. To one of the containment chambers. Cisco locks them in, saying he’s buying time. About 10 seconds of time – Killer Frost points out that her palmscan still works. Then Barry arrives. He tells Killer Frost that she should fight this. She agrees – but she doesn’t want to. She forms an ice wall and leaves.
Cisco isn’t happy. He thinks they should have taken Caitlin to a hospital. Which would have exposed her as a meta. Which Cisco thinks she’s going to do now anyway. Barry intervenes between Julian and Cisco’s argument. Then decides he’s going to run to the future. Now. Caitlin may be out there, but Barry can go and be back in the same instant. Wally says that last time it was an accident, so how is Barry going to do it now? With Wally’s help.
Barry arrives in the future, which looks a bit tatty around the ages. He’s arrived at the right date. Then a woman asks if it’s throwback Thursday; it’s Top and she’s joined by Mirror Master. Neither has seen the Flash for a while, and Mirror Master says it’s his town now. Top corrects him to their town. Barry manages to get away though.
Barry’s apartment is abandoned and trashed. Then Cisco shows up. He had a feeling it was Barry; one he hadn’t felt in a long time. Cisco has worked out that Barry is from 2017, and decides it must be about Savitar. Barry needs to talk to himself.
S.T.A.R. Labs is closed down. H.R. has moved on to other things. Caitlin never returned after becoming Killer Frost. Future Barry pushed everyone away, saying they were a constant reminder of what he lost. Future Barry never leaves the place. When Barry finds him, Future Barry tells him he shouldn’t be here. To go home. He can’t save Iris. Future Barry can’t say who Savitar really is – because he doesn’t know.
With the mission failed, Barry decides he has to go home, even though Cisco would like him to help. However, the portal doesn’t open. Cisco tells him that ate least he can get back to the same time, no matter how long he stays in the future. Cisco wants to get the team back together. He wasn’t able to because, in his battle with Killer Frost, she froze his arms off. No hands, no powers. He has mechanical arms now.
Julian is working at Iron Heights. When told that Barry is from 2017, Julian says it’s the year it all began. Killer Frost is also there, locked up. Barry apologises for failing her, but she’s glad. She doesn’t want to go back. Barry is no match for the God of Speed. Savitar showed her the way. He gave her a cure for her illness – to embrace who she really is. Killer Frost knows who Savitar is. She won’t share, though, but Barry will be so surprised when he finds out. It’s definitely sounding as if Savitar is someone that Barry knows. Killer Frost thinks Barry’s protégé went toe to toe with Savitar.
Wally is in a wheelchair and totally unresponsive. Cisco explains that, when Iris was killed, Wally went into a rage and confronted Savitar by himself. Joe found him the next day with a shattered spine. He’s been like that since. Joe is at Iris’s grave, and doesn’t want Barry there. He doesn’t know this is Barry from the past. Barry is not happy with Future Barry, for not being there when he promised. For any of them. Future Barry tells Barry that, even though Savitar ends up locked in the Speed Force forever, he’d already won by then. By taking everything away.
So, not a terribly helpful trip into the future so far. Nothing learned and everything has fallen apart. More hints that Savitar is someone known, but this is still not revealed. Caitlin is out there as Killer Frost and seems to be enjoying it. Barry could still make things a bit better in the future before returning to the past though.