When we last left off Iris West was just murdered by Savitar or was she? As speculated, HR switched places with Iris and was the one to take the fatal blow for the team. We see that HR made the decision out of guilt for leading Savitar to Iris and uses his transformer to change his appearance to Iris and her to HR. Tracy sees that HR has been mortally wounded. Before he dies, HR professes his love to Tracy and asks her to move on. Also, before HR dies he gives Barry a message to give to Cisco.
Meanwhile, the battle between Cisco and Killer Frost is still ongoing. When Killer Frost is about to deal a fatal blow Savitar arrives with Speed Force Bazooka in hand telling her to let him go as they need him.
Barry, Iris and Joe go to the time vault and see the headline byline return to be Iris West-Allen. They rejoice that the future has changed. At STAR Labs, there is little time to mourn HR’s sacrifice as Julian has returned with a cure for Caitlin. With the future now changed, Team Flash realizes that Savitar will cease to exist. However, there are many hours left before the paradox catches up to Savitar and they know he is planning something to prevent that from happening.
At Savitar’s lair, he gets a memory of Iris being alive and Julian possessing the cure for Caitlin. Savitar knows time is running out so he needs Cisco to adjust the Speed Force Bazooka so that it splits him up like Voldemort’s Horcruxes so that he can be scattered throughout time. Cisco refuses but when Savitar mentions Julien’s cure and threaten to kill Caitlin that he complies.
Meanwhile, Barry has figured out a way to reach out to Savitar and the two meet at some warehouse. Barry knows that within Savitar is still a piece of him. Barry shares a favourite childhood memory that Savitar also fondly recalls. Barry implores Savitor to come with him back to STAR Labs so they can help him.
Surprisingly, Savitar does come to STAR Labs but Team Flash isn’t happy to see him. However, Iris approaches Savitar and gently touches his face promising to help him. Savitar wonders what Team Flash can do and they tell him that Tracy can help. However, Tracy is in no mood to help the man who killed the love of her life so she walks off. Iris knows who can talk to Tracy to get her to help: Harry Wells. Harry has to tell Tracy that he isn’t HR but says that he knows HR and what he means to the team and what his sacrifice was for.
Unfortunately we don’t quite know how Tracy would have helped Savitar because on the pretense of bringing back Caitlin and Cisco, he actually decides to blow up the Philosopher Stone forcing Barry and Wally to evacuate everybody. Before Savitar leaves, he shares a future memory of how Team Flash fashioned some sort of device to stop Deveaux (this is the second time this name has been mentioned, the first by Abra Kadabra).
At Savitar’s lair, Cisco has finished with the weapon. Cisco tries to get Killer Frost to see sense and how Savitar will kill her once he has gotten what he needs from her. However, Killer Frost has no interest in betraying Savitar. With Killer Frost getting ready to ice Cisco, Gypsy arrives and saves him by throwing through a portal. Cisco wonders how Gypsy knew he was in trouble and she says that she sensed he was in trouble through the multiverse because they are connected in some way. We see that Gypsy vibed them to Barri and Iris’ apartment.
All of Team Flash is reunited and plans are made on how to defeat Savitar.
In the woods, Savitar is about to realize his plan on becoming a God. Savitar uses the Speed Force Bazooka and opens up a portal. We realize that Savitar needed to Killer Frost so she can ice Black Flash. With the Black Flash gone, Savitar is ready to be split up. Killer Frost shoots the bazooka at Savitar and we see him start to split apart but then comes together and we see Jay Garrick come out. Cisco actually rigged the weapon as a Speed Force Skeleton Key.
A battle ensues between Gypsy, Cisco and Killer Frost and Savitar versus Kid Flash and the Flash. In the Killer Frost/Gypsy/Cisco battle, it ends with Cisco offering Caitlin the cure and we see Caitlin come back. When Savitar is about to kill Cisco, Caitlin uses her powers to push him away.
The battle between the Flash and Savitar resumes and the Flash ends up speeding his way into the Savitar suit and it looks like he is going to kill him. However, the Flash vibrates to destroy the suit and spares Savitar and simply knocks him out. Thinking they’ve won. the Flash lets his guard down and Savitar moves to kill Barry but a gun shot rings out and Savitar falls dead at the hands of Iris. We then see the paradox catch up with Savitar and he disappears from existence.
The next day, we are at HR’s funeral, Iris gives a lovely eulogy and everyone has a final moment with HR. Barry then gives Cisco HR’s message. Barry, Cisco and Julien see Caitlin lurking and we see her not sporting her Killer Frost costume. Caitlin reveals she is not taking the cure as she needs to figure out who she is now as she is neither Caitlin Snow nor Killer Frost.
Back at Barry and Iris’, the couple take a moment to relax now that everything is over. Iris then pulls out the wedding invitations saying how she was afraid to send them out for fear of her future. Barry then speeds off to deliver all of them. With everything looking so bright, we just know something is going to happen. That something is earthquakes in Central City. But these aren’t earthquakes but Speed Force Storms looking for a speedster to imprison since Jay left.
Barry and Team Flash go outside Star Labs and sees the storm wreaking havoc on Central City. Barry knows that he has to be the one to go. Barry gets Wally to promise to be the new Flash and get Harry to stay on Earth-1 for awhile and wants Cisco to be the new leader of Team Flash. Iris doesn’t understand why Barry needs to be the one to go. Barry tells Iris it his penance for creating Flashpoint. We see the Speed Force appear to Team Flash as Barry’s mom telling him it is time for him to go. Before Barry leaves, he tells Iris that she will always be Iris West-Allen but that she needs to move on and live her life.
We then see Barry and his “mom” go into the Speed Force together and so ends season 3.