This episode starts right where its predecessor ended as Barry holds on to the love of his life, who has been stabbed by Savitar, as had been predicted months ago. However, in a shocking (?) twist that has become par for the course for The Flash, it is revealed that HR has sacrificed his life to protect Iris. He uses the fragment of Savitar’s suit at S.T.A.R. Labs and finds Iris. He subsequently frees her and uses the device from his earth to change his facial appearance to Iris’ and Iris’ appearance to his. Killer Frost discovers Wells, who now looks like Iris and captures him. Iriswalks away looking like HR. Flashback to the present and Iris reveals herself to a grief-stricken Joe and HR reveals himself to Barry. The stab proves deadly, and HR succumbs on the very spot that was to be the premeditated spot of Iris’ last breath.
Iris’ survival meant that Savitar’s existence would be an anomaly and the Speed Force would seek to rectify the problem of his existence soon. Savitar quickly reverts to Plan B and tricks Team Flash into trying to save him. At S.T.A.R. Labs he uses the Philosophers Stone to attackand distract them. The purpose of this distraction is that Savitar has held Cisco hostage and has commanded him to alter the Speed Cannon a bit so that Savitar would be a constant within time, existing for eternity. This would make him the god-like being he suggested he was and would allow him to wreak havoc over all of the time. Little did he know that Cisco reprogrammed the Canon to set Jay Garrick free from the clutches of the Speed Force.
With the addition of Garrick, a final battle ensues. Gypsy, Barry, Jay, Wally, and Cisco combine to fight Savitar and Caitlyn. In the deciding scene, Barry phases himself into Savitar’s suit of armor and pushes his psychopathic remnant-from-the-future out. Barry dismantles the suit and spares his time remnants life. As he walks back toward his team, Barry’s disgruntled time remnant charges toward him. A gunshot is heard in the distance as Barry turns around to see his time remnant on the ground, the paradox catching up to him, and Iris right behind him, wielding a gun.
Team Flash, Gypsy, and Jay attend HR’s funeral where Tracy (HR’s girlfriend) is beside herself. Suddenly, the sky starts assuming volatile pink-ish hues, bolts of oddly colored thunder shoot out from the clouds, and the ground begins to quake. A portal subsequently opens and the Speed Force, in the form of Nora Allen appears before Barry. Since Jay had been released from the speed force thanks to Cisco’s contraption, the Speed Force had no speedster in occupance. The Speed Force, assuming the likeness of Barry’s deceased mother, offers Barry a peaceful rest for all that he has done. Barry understands this and says goodbye to the love of his life, after having worked tirelessly to save her in the preceding months. Barry Allen then walks through the portal, presumably never to be seen again.