This episode of the Flash has Barry travel to Earth 3 to ask Jay Garrick for help with Savitar. The two locate Alchemy, who is trying to use the Philosopher's Stone to create more metahumans. They defeat the villain, but Savitar shows up at fights Jay. Savitar easily gets the better of Jay and nearly kills him. Barry manages to take the Philosopher's Stone from Alchemy, which causes Savitar to get pulled into the Speedforce. Barry unmasks Alchemy to find Julian underneath.
At Star Labs, Julian reveals that he had no idea that he was Alchemy and admits that he has been blacking out. He also reveals that he first found the stone while following visions of his dead sister. They keep the stone locked in the ancient box it was found in. Savitar begins showing visions of Dante to Cisco, enticing him to open the box. Savitar appears and attacks Barry. Wally tries to help, but the god defeats them both. Caitlin convinces Cisco that Dante isn't real and Savitar is tricking him.
Julian expresses his desire to help and the team uses him as a conduit to communicate with Savitar. Savitar blames Barry for imprisoning him in the future and wants revenge. As the team watches, the speed god reveals that one of them will die, one will betray them, and another will suffer a fate worse than death. Barry and Jay decide to throw the Philosopher's Stone into the speed force in order to end the threat. There is a chain reaction, and Barry is thrown into another time period. He sees himself facing Savitar, who has Iris hostage. He witnesses Savitar kill Iris before Jay pulls him back to the present and reveals that he was in the future. He tells Barry that people aren't supposed to know their futures, which is why speedsters only go to the past. He also tells Barry that the future is not fixed and that the future Barry saw was only a possible future.
Jay returns to Earth 3, and the rest of the team has Christmas at the West house. Wally is gifted the Kid Flash uniform and Julian arrives, not wanting to spend Christmas alone. Barry and Iris leave the party and Barry surprises, Iris. He shows her an apartment that he bought, indicated that he wants the two of them to move in together. The episode closes with the couple embracing in their new home.
This episode was about as good as last season's mid-season finale. We see Savitar completely replace Alchemy as the main antagonist of the season, as the team learns that Alchemy is Julian and that he didn't even know about his villainous alter-ego. This was an interesting twist for many and one that is sure to have consequences later on in the season. The Philosopher's stone operates a little differently than what we were originally led to believe. The stone is Savitar's link to the physical world and when it is locked in its mysterious box, Savitar is pulled out of reality. With the stone being thrown into the speedforce, we can only guess at how Savitar will return.
We also get another guess appearance by Jay Garrick, played by the now legendary John Wesley Shipp. We are given a brief look at Earth 3 and Jay's activities as a hero on his own Earth. Mark Hamill returns as Earth 3's Trickster, who is seen to be far more deranged than the one we have seen back on Earth 1. Seeing Jay and Barry together was a treat and Jay's knowledge of the speedforce has placed him into a mentor-like role. It was interesting to see that Savitar knew of Garrick and that he was easily able to defeat the veteran speedster. It showed just how much more powerful Savitar is than the other speedsters.
The ending of this episode granted viewers some hope after the tragic vision of the future that Barry experienced. Wally is gifted his Kid Flash suit, Julian comes to the christmas party, not wanting to be alone, and Barry and Iris plan on moving in together and share an embrace before the close of the episode. This gives the viewers some closer to the immediate story arc and spares us from a crippling cliffhanger to ponder for the next month. This was a good episode and shows that Flash is still able to sustain itself into its third season.