“Worlds lived, worlds died. Nothing will ever be the same.”
The crossover starts on Supergirl S05E09 Crisis on Infinite Earths: Part One (I), Batwoman S01E09 Crisis on Infinite Earths: Part Two (II), The Flash S06E09 Crisis on Infinite Earths: Part Three (III) and Arrow S08E08 Crisis on Infinite Earths: Part Four (IV)
Sara, Ray and Mick are shocked to discover that the Legends have become famous. The Legends discover that their new problem is Rasputin. Constantine thinks he knows the reason for new time blips and informs the team that it won't be easy to defeat.
When a new blip lands the Legends in 1947 Los Angeles, it puts them on the trail of Benjamin “Bugsy” Siegel who seems to take pleasure in fraternizing with Hollywood Elite. Sara, Ray and Constantine devise a plan to capture him while Ava and Rory sit on the sidelines for the time being. They soon realize that they need to worry less about Bugsy and more about his girlfriend. Ava is struggling with being on the sidelines with Rory. Meanwhile, Nate accompanies Behrad to his dad’s birthday, where Nate meets Behrad’s sister, Zari, who seems familiar to him.
When the Legends discover a new Encore, Sara, Rory and Ava end up crashing a high school reunion to attempt to stop a serial killer from finishing unfinished business. The Legends devise a plan to send Nate, Ray, Nora, Behrad and their hostage Zari, back in time to try and intervene in order to try to save everyone including them. Meanwhile, Constantine is annoyed that Charlie has been squatting in his old home, but it might be the blessing in disguise they were not looking for.
When Sara is called away on business, she leaves Ava in charge and Ava tries to impress the team as they try to take on their latest Encore, Marie Antionette. With Zari still on the ship, Behrad convinces the team to bring her along on the mission which they all hope isn’t a mistake. Meanwhile, Constantine finally confronts someone from his past with the help of Charlie, which leads him on a journey through his past.
With Sara still away from the Waverider, the Legends find a new Encore with Ava’s new invention, the Prognosticator, and must now try to defeat Genghis Khan in 1990s Hong Kong. Constantine’s life is hanging in the balance, and Ray, Nora and Gary all try to help him, but Constantine tries to make a deal with Astra instead. Meanwhile, Behrad has been confused about Charlie’s recent behavior, but they all learn why Charlie is trying to out run her past and from what
Ray plans a date night for him and Nora, but all goes awry when an Encore shows up making the team think on their feet and create a lie to keep the Encore at bay. While trying to fool the Encore, Ava learns what Sara was really doing while she was away and confronts her. Charlie and Constantine make a deal to work together, which will benefit both of them. Meanwhile, Rory is upset when he gets negative comments about his book, so Zari helps track down who the critic is, and Rory gets more than he bargained for.
The Legends continue their hunt for pieces of the Loom of Fate and find themselves face to face with William Shakespeare. Ray, Nate, Rory, Constantine, Charlie and Behrad stay a little longer on the mission making things worse after lying to Sara. Meanwhile, Ray and Nora make another big life decision that leaves the team surprised and best buds, Nate and Ray, on the outs.
Sara, Constantine and Charlie find themselves in British Columbia searching for another piece of the Loom, but they run into a problem they couldn’t have foreseen. Zari has been having trouble feeling like herself, so she goes on meditative journey at the suggestion of Behrad. Meanwhile, Ava volunteers to try and help Rory with a personal problem.
With Sara recuperating from her latest battle, Charlie starts to notice something might not be right with her. Still searching for the Loom, Constantine and Zari find themselves trapped in a 1910 boarding house with a slew of out-of-time Encores. Meanwhile, Ava, Gary and Rory take a trip while Nate and Charlie hold down the Waverider.
Everyone is eager to use the Loom of Fate, but the team must decide who they want to bring back first leaving Charlie to make a tough choice. Sara struggles to understand what has happened to her and with the help of Constantine and Ava, they try to figure out how to help her. Meanwhile, Rory has a guest on the ship that he is trying to impress.
The Legends find themselves going back to college and form a sorority in order to try to retrieve an ancient artifact called the Chalice of Dionyus that will help Charlie operate the Loom of Fate. Proud to be back at his college, Nate falls under Dion’s spell, letting him know of Sara, Astra, Ava and Charlie’s plan to get the cup. Meanwhile, on a father-daughter weekend, Rory takes Lita on a college tour, but Rory bails on Lita for an unexpected reason.
After drinking from Chalice, the Legends have immortality for 24 hours, which gives them time get to the Waverider and use the Loom of Fate. However, they quickly discover that the sisters have stolen the Waverider and they are stuck at Constantine’s house in the middle of nowhere in London during a Zombie Apocalypse. Meanwhile, Gary is left on the ship and once he discovers what is going on, he takes something important to the sisters.
After Charlie does the one thing that goes against her nature when it comes to her sisters, she tries to protect the Legends by scattering them in different television shows. Of course, in true Legends style some can’t just be blissfully ignorant and happy but figure out a way to end up messing with the system.
Still controlled by the Fates, the Legends find themselves in 1984-esque world, they soon discover that things aren't as they thought they would be. The Legends must convince the civilians to trust them and stand up for their right to choose, but the Fates don't make it easy by resurrecting the Encores once again.