Ben emerges from a dark room into the wrecked remains of QL HQ where it is snowing through a hole in the ceiling. Ian steps out from the shadows holding a torch to explain it’s a nuclear winter. Ben sees how aged Ian looks and realizes he’s leaped into the future.
In 2023, Ian is alerted that a quantum signature has been detected. Everyone rushes to their terminal but the signature disappears. Janis joins them. The signature appears and disappears again. Janis points out the accelerator wasn’t designed for traveling to the future.
The year is 2051, and Ben’s essence is being pulled back into the past by the accelerator. Ian urges Ben to fight it so they can explain the mission.
At HQ, Janis doesn’t know why Ben’s leaped into the future.
In the future, Ian explains the government’s blamed the QL project for how badly things have gone. They sent Martinez to reverse everything Ben did in the past, after sending him initially to kill Addison. After Ian warned Ben about it and Ben leaped, it bought time for Ian to work out some code. He shows it to Ben and tells him to memorize it. Ben’s being pulled back into the past. Ian tells Ben to give the code to Ian in the past.
Ben leaps into 2018 and walks into QL HQ as it’s being constructed. He sees Magic, Jenn, and Ian walk in together, talking about trivia night.
Janis explains that this is the leap Ben needed her help to program. Ben’s leaped into himself in 2018.
When Addison makes contact, Ben gives her the code Future Ian gave him with the message, “Remember that we need each other.” 2023 Ian has no idea what to do with it but is willing to try to figure it out.
Ian and Janis both warn Addison to tell Ben not to change anything in the past since he’s now in his own timeline.
In 2018, Ben and Addison collide and catch the team’s attention. They realize Ben and Addison are going on a date. Hologram Addison realizes it’s the night of their first date. Magic heads out for a visit with Al. Jenn gives him a couple of Cuban cigars to give Al.
Addison warns Ben he has to follow through with their first date otherwise they may never fall in love.
At the restaurant, Hologram Addison prompts a very nervous Ben to recreate the first date.
Janis and Ian examine the code from Future Ian together. Janis gives Ian a pep talk. Ian fills Janis in on how they struggled when they first joined the project. An alert pings that Leaper X has arrived.
In 2018, Addison informs Ben that Leaper X has arrived but is a long way off still. Ben isn’t willing to play out the date and tells 2018 Addison that they have to go.
Out in the parking lot, after apologizing to Hologram Addison, Ben tells 2018 Addison that he’s traveled from the future to save her life.
Knowing that Martinez is headed for HQ, Ben tells 2018 Addison to drive his car to his place and lock herself in, trusting no one.
Ben leaves to run back to HQ. 2018 Addison calls Magic to talk about what Ben said to her.
Ben and Hologram Addison return to HQ, planning to ambush Martinez. When they get back to the project offices, 2018 Addison is waiting with a weapon trained on Ben.
Ben tries to talk 2018 Addison down, moving the gun off him, but she fires, hitting a fire extinguisher. Ben and Hologram Addison escape. 2018 Jenn arrives and initiates lock-down.
2023 Jenn realizes Ben is trapped by her lockdown and lets Magic know that Leaper X just entered the building so he’s locked in with their past selves. Jenn pulls Addison out of the imaging chamber so she can help Ben beat her system. Arriving, she directs him to hide behind some boxes. Her guards miss him because they always sweep north to south and the boxes block the cameras.
2023 Jenn tells Ben that Martinez is headed for Magic’s office. She gets a little emotional as she cautions Ben to be careful.
Ben finds Martinez. Addison enters the office armed. Martinez has leaped into Magic. Ian and Jenn join them. Ben tries to prove that Martinez is the danger, but fails to answer personal questions about Ian, Jenn, and Addison. Martinez has the answers and Addison has Ben thrown into a confinement cell.
Martinez gives the team orders as Magic. He tries to get Addison to leave her sidearm behind since she got emotional with Ben earlier, taking a shot.
In the cell, Magic appears as the hologram to talk to Ben. He points out the people we love are our greatest weakness. Ben’s risked everything to save Addison, while Magic did the same to bring Sam Beckett home.
Magic tells Ben that Jenn says he has to write “Turtle Time” on the cell wall. Ben says he doesn’t have a pen. Magic tells him he always keeps on in his jacket, inside breast pocket. Just then, Martinez enters, still dressed as Magic. He enters Ben’s cell.
2018 Ian and Jenn are watching the security cams. They can’t hear what Martinez says to Ben after he enters the cell. Ian notices Ben writing the code in a notebook on footage from earlier. Ian finds the notebook.
In the cell, Ben tells Martinez they destroy the quantum accelerator in the future, meaning Martinez can never return home. Martinez explains his mission is to neutralize the danger of time travel to the world. Destroying the accelerator was his idea. He also had Ziggy run the scenarios and knows that killing only Addison won’t fulfill his mission. He has to make sure the entire team dies.
As Martinez turns to leave, Ben grabs him. Martinez easily fights him off, but Ben gets the pen.
2018 Addison notices the cigars Jenn gave Magic to give Al are still in his briefcase. 2018 Ian’s examining the code when 2018 Jenn notices Ben writing “Turtle Time” on his cell walls. They rush down to his cell. “Turtle Time” was the password Jenn made up for herself when she joined the project in case she was ever visited by her future self. She and Ian realize Ben is who he says he is.
Ian asks Ben about the code which looks to them like a cheat code for a complicated video game. Ben tells them he got it from them.
2023 Ian notes that comment.
Addison catches Martinez setting the accelerator to implode. Martinez pulls a gun on her. Ben rushes in and Martinez’s gun goes off, hitting Addison in the arm. Martinez and Ben fight, falling into the accelerator chamber. They square off and disappear.
Ben and Martinez return to Georgia’s Island Asylum. They continue to fight.
Ian reasons that if Future Ian wrote the cheat code, Ben could leap to any point in the day in question, fixing anything he changed.
In 1954, Martinez is beating on Ben when they leap again. They land on the USS Montana. Ben realizes he’s still Rossi and orders the officers on the bridge to detain Martinez. Martinez dispatches them both and heads for Ben. Ben remembers the advice he got as a boxer.
He manages to subdue Martinez. They leap again.
2023 Ian starts entering the code into the system.
Ben and Martinez land in Salvation. They keep fighting.
2018 Ian enters the code into the system but gets an Interface Error message.
2023 Ian gets the same error message.
Ben and Martinez are still fighting. Martinez gets a hold of a gun.
2023 Ian and 2018 Ian realize that, like a video game they were never able to beat, they need a second player in order to succeed. They need to enter the code at the same time.
In Salvation, Martinez prepares to shoot Ben. Suddenly, he’s shot from behind and his body topples off the balcony. Behind him, Miss Frankie holds a smoking pistol. She checks on Ben/Diego de la Cruz.
In 2018, Ian has no idea how to contact their future self. Addison hits on the concept of quantum entanglement that Ben tried to explain to her. She points out that all of the Ian’s throughout time have existed in a shared state so they exist as one.
Tapping into that, they enter the code together. Ben leaps back to the moment in 2018 where he entered the day of the first date.
Discussing things with Hologram Addison, he realizes that some of the things he did before they dated were missteps. He asks her permission to make it right and she gives it. He walks to where he and 2018 Addison bumped into each other and kisses her instead. It’s a welcome move and she smiles at him while the team cheers. Ben leaps.
In 2023, the team prepares to welcome Ben home. His form begins to appear in the accelerator. End credits.