The episode begins with a montage showcasing the events of the season.
Rip gets Gideon to turn the ship back on. He pilots a course to rescue the Legends, but discovers that he and the Waverider are actually miniaturized and stuck on Thawne's desk in STAR Labs. He turns on the ship's cloaking device and flies out a window.
The Legends experiment on a radio, trying to send a message to Rip. Sara consoles Nate after Amaya's death. Ray and Jax believe they have transmitted a signal to Rip, but they discover that Rip and the Waverider are really already inside the room, just in the miniaturized version. They determine that Thawne shrunk the Waverider using Ray's ATOM technology, and that they need to steal it back before they go back to fix reality.
Ray and Jax find Ray's suit in STAR Labs, but are interrupted by Damien Darhk. He prepares to kill them, but Rip and the tiny Waverider attempt to intervene. While Darhk is distracted, Mick knocks out Darhk, and Ray successfully zaps the Waverider back to its normal size. The team flies away in the ship.
The team prepares to go back to WWI and get the Spear before the Legion does. They realize that in doing so, they will erase the current versions of themselves, but do it anyway.
Ray flies to the burial spot on the WWI battlefield, and collects the blood of Christ. It's quickly stolen by Thawne, who destroys it. He then takes Ray's heart out of his chest, killing him.
The team processes Ray's death, but realize that it ultimately doesn't affect the mission since the older versions of themselves are aberrations. They realize that past-Mick is about to meet Snart, and they go to intervene.
Snart smacks past-Mick, and then joins the rest of the Legion in a tent. Thawne explains that there are two sets of Legends, and that he himself is also from the Doomworld future. Thawne leaves to get backup.
The team watches their past selves leave the Waverider. They enter the past Waverider, where they run into past-Sara. They have an awkward exchange, which past-Sara finds suspicious.
Nate runs into the past versions of Stein, Jax, and Amaya. Nate gets taken-aback by seeing Amaya alive again, but distracts the team by telling them that Christ's blood is in the Galapagos Islands in 1984. Stein and Jax leave the room, and Nate hugs Amaya.
Mick finds the Spear of Destiny, but he and Rip wait for Nate to join him. They get ready to leave, but Sara and Jax see that the rest of the past Legends are about to board the Waverider. The current versions of Mick, Rip, and Nate are stuck inside the Waverider, because if they run into their past selves, it will wreck time itself.
Sara and Jax attempt to stop the past Legends from getting on the ship. Their lies barely convince the team.
The past Legends within the ship wonder what's going on. They call the past Legends outside with their comms, and suspect that they're the Legion in disguise, and the team beats the future Legends up.
The past Legends realize that Jax and Sara are who they say they are, and bring the future Legends onto the ship. Past-Sara questions that. The team begins interacting with their past selves, causing a time quake. Past Ray and Amaya realize that their future selves are dead. Sara explains that the Legion got the Spear, and past-Sara storms off.
Past-Sara asks Sara if she regrets not using the Spear. Sara says that she doesn't, because she doesn't feel worthy enough to use it in the first place.
Nate talks to past-Nate about their feelings for Amaya. He tells past-Nate not to hide his feelings for Amaya, and to do the things with Amaya that he wishes he could've done.
Outside, the battle commences. The Waverider's shields are down, due to the Legion firing at it. Both sets of Legends get ready to jump in time, but Rip thinks that it will cause an even larger aberration. Past-Sara does it anyway.
A time storm commences as the Waverider attempts to fly away before crashing onto the ground.
The team realizes that the Waverider has sustained permanent damage. Sara suggests that the past-Legends make it to the other Waverider and make it out successfully, even if all of the current Legends die in the process. They agree on the plan.
The two sets of Legends fight the Legion of Doom. Merlyn and Snart fire at Firestorm and Ray, sending them both to the ground. Merlyn begins to shoot another arrow, but post-Doomworld Jax blocks it, dying in the process.
Mick pins Darhk up against a tree, but is temporarily distracted by Snart. Snart kills post-Doomworld Mick, but then pre-Doomworld Mick shoots him down.
Darhk kills post-Doomworld Nate, and then has a sword fight with pre-Doomworld Sara. Pre-Doomworld Rip takes the Spear to the Waverider, to take to the Vanishing Point. She gets ready to kill him, but post-Doomworld Sara knocks him out.
The remaining versions of the Legends prepare to leave, but are stopped by an army of Thawne and his past selves.
Thawne tells the team that he will spare their lives if they give him the Spear. Sara decides to use the Spear instead, as Thawne begins to fight the team. Sara activates the Spear.
Sara is suddenly in Laurel's apartment, watching The Wizard of Oz. Laurel comes in with glasses of wine. Sara questions the reality, and Laurel tells her that this isn't real, but it can be if she chooses to change things with the Spear.
Sara says that Laurel was always the better of the two of them, and that she herself is too damaged to use the Spear. She contemplates changing everything bad that has happened to both of them, but Laurel knows that she won't. Laurel tells Sara that she knows she will do the right thing, and that Laurel won't be far away anyway.
Sara returns to the WWI battlefield, where Thawne has gotten the Spear out of her hands. He attempts to activate it, but Sara has de-powered the Spear. Thawne attempts to kill Sara, but Black Flash runs in and kills him first. He and the Spear disappear from existence.
Black Flash kills the rest of Thawe's duplicates, before staring Sara down and running away. The rest of the Legends wake back up, along with post-Doomworld Sara, who proceeds to be erased from reality. The team heads back to the Waverider.
The Waverider flies away. Sara approaches Darhk and Snart in a cell. She explains that she brought Malcolm back to 2017, but that she won't be doing the same for them.
Mick brings Snart back to 2014 Central City, with the promise of wiping his memory and bringing him right to the moment before Thawne recruits him. He tells Snart that his death with the Legends makes him a better man, and then wipes his memory.
Sara brings Darhk to 1987 and wipes his memory as well.
Amaya tells Nate that she's ready to leave the Legends, and Nate offers to go with her. Amaya then says that she's willing to stay with the Legends, even if it means prolonging her destiny.
Sara finds Rip preparing to leave. He explains that he feels inadequate as a teacher and captain now that the Legends are so well-equipped. Sara grants him permission to leave the team.
The team plots a course for Aruba, 2017, but the Waverider crash lands somewhere else instead - a distinctly different version of Los Angeles, 2017. The Legends have broken time itself.