Barry's cuddling with an unresponsive Iris after Savitar's attack as Joe watches from above. Barry's surprised when H.R.'s drumsticks fall out of Iris' pocket. On the roof, H.R. reveals himself to be Iris. The real H.R. is in Barry's arm. Through a flashback, he sneaks into Savitar's lair and rescues Iris. He switches their faces using his device. Iris is not on board with the plan, but Killer Frost knocks her out. H.R. as Iris convinces her not to kill "H.R."
Savitar kidnaps Cisco. He wants him to alter the speed bazooka. Cisco's not interested in helping, but Savitar threatens to kill Caitlin. He also tells Cisco that Julian's returned to STAR labs, and is currently telling the team that he can cure Caitlin. Cisco reluctantly agrees to help. Back at the lab, Barry tells Iris that he has another way to try and reach out to his future self.
Savitar-Barry meets present Barry, who tries to get through to him using their shared memories. Barry's confident that he's still in there. He convinces Savitar-Barry to return to STAR labs with him. Once there, Julian wants to know where Cisco and Caitlin are, but Savitar-Barry wants help first. Iris reaches out to him. She and Barry promise to make him feel like he's part of the team. He's hesitant, but agrees to bring them Cisco and Caitlin.
Except he's lying. He tries to blow up the lab instead, but Wally and Barry manage to get everyone out. Once Cisco finishes his work, Killer Frost is about to kill him, but Gypsy shows up to rescue him. She saw in a vibe that he was in trouble. Savitar-Barry puts his plan into action. He opens the speed force and has Killer Frost take care of the time wraiths that try to stop them. But the gun Cisco made frees Jay from the Speed Force.
Barry, Wally, and Jay fight Savitar while Gypsy and Cisco face off with Killer Frost. Cisco gives her the cure and a choice. Savitar tries to kill Cisco, but Caitlin stops him. Barry pushes his future self out of the suit, and uses it against him. Savitar-Barry is fine with that because he believes the anger will still be Barry's downfall. Barry doesn't kill him. When Savitar-Barry moves to attack, Iris steps in with a gun and shoots him.
At H.R.'s funeral, Iris gives a beautiful eulogy to her hero. Tracy, Julian, and Wally say goodbye while Barry shares H.R.'s last words with Cisco. They see Caitlin standing nearby. She gives the cure back to Julian. She's not Caitlin anymore, but she's not Killer Frost either. She tells her friends she wants to figure out who she is now on her own.
Back at their apartment, Barry and Iris are making wedding plans. Earthquakes begin ravaging the city. Everyone meets back at STAR labs, and they realize the Speed Force is coming apart. It needs a prisoner inside to keep it steady. Barry knows it has to be him. He says goodbye to his friends and family. He asks Iris to live her life without him, and then he walks hand in hand into the Speed Force with his mother.