Barry Allen, also known as the Flash, is at Star Labs when he receives an alert that the Reverse Flash is back. Barry puts on his suit and goes after him. While chasing the Reverse Flash, Barry unintentionally opens a breach to another universe.
He finds himself in the universe of The Boys, where superheroes are not the noble figures he knows but instead corrupt individuals with their selfish agendas, concealed by the company that provides them with superpowers—Vought.
Confused and disoriented, Barry tries to run back home to his universe but struggles to reach the necessary speed to return home.
Meanwhile, at Vought Tower, Homelander sees footage of the Flash's arrival and sees him as a threat to his plan. He decides to pursue Barry with the Seven, consisting of himself, A-Train, Black Noir, Sister Sage, The Deep, and FireCracker.
When The Seven attack Barry, the boys show up to rescue him. They use Starlight's light powers to blind them and take Barry back to their home base.
back at their base Butcher pulls up a chair in front of Barry. "Who are you, Mate? Because frankly, I don't trust you. We only saved you and brought you here because the others are good people, and I think you might give us an advantage against the Seven." with a British accent, pointing at him.
"I'm Barry Allen. Where I'm from, they call me the Flash, this is going to sound crazy, but I'm from another earth ." Barry rambled and paced through the room, trying to explain himself.
"Crazy is just another Thursday for us." Go on," Butcher said, giving Barry the benefit of the doubt.
Frenchie walks in, "It is C'est possible the many worlds interpretation of quantum mechanics hints at the possibility of multiple different universes."
"So, can I use this whiteboard?" Ok, imagine there are multiple Earths, one where the Nazis won World War II and one where Kennedy was never assassinated. All these Earths occupy the same space but vibrate at different frequencies, so they can't see each other. Barry is getting up and trying to explain the multiverse.
But if you could run fast enough to open like a breach, you could travel between universes, so you're a speedster like A-train. Frenchie asks with a French accent.
"Yeah, I was chasing my greatest enemy, the reverse flash, when I must have run too fast and ended up. It has happened before; hopefully, my team will find me one of our members Cisco can open breaches." Barry tries to explain what happened to him.
"Give me a moment to discuss this with my team." Butcher is unsure of whether or not to trust Barry.
"Ok," Barry responds.
Butcher and Frenchie walk into another room to chat with the rest of the team: Annie/Starlight, Hughie, Mother's Milk, and Kimiko. I'm not bloody sure I trust this twat" Butcher is still distrustful of Barry.
"Well, we've not got much of a choice; he's probably our best bet against the seven, and remember, you're not in charge anymore, Butcher, I am." Mother's Milk points at Butcher, letting him know he's in charge now.
"We still have the virus. I need bloody time to adjust it, Butcher responds.
"We are not using the virus; that is insanity, and how are we supposed to adjust it when the scientist working on it got away? If you noticed, we don't have time. Homelander's plan to assassinate the president is that in a few weeks,
Barry's powers could give us an advantage against Homelander and The Seven Show of Hands, who say we trust Barry." Starlight disagrees with Butcher's plan about the virus, and the rest of the team except Butcher raises their hands.
"Fine, I'll bloody adjust it myself." Butcher is pissed off at the boys' heads for the elevator and leaves whilst he is in the elevator. Starlight's right, you know you're out of time, Butcher, you need to release the virus as is now." The imaginary Joe Kessler Butcher sees because of his tumour.
"What about Ryan, Annie, and Kimiko?" Butcher asks Kessler
"Casualties of War: You're a soldier, and you know that sometimes to do what's right, you have to get your fucking hands dirty." Kessler tries to convince him to release the virus now.
"Please don't do this, Butcher. This isn't you remember what you promised that you would keep Ryan safe?" the imaginary version of his dead wife Becca is trying to keep Butcher from crossing a line he can't go back from.
"Don't worry, Becca. I won't, but to adjust the virus to kill Homelander We need to find the scientist" Butcher leaves to look for Samhir, the scientist.
The boys return to Barry's room and say, "Okay, Barry, we believe you, but we don't know how to help you. Why can't you run at superspeed to open a breach home? We need your help with Homelander and the seven superpowered individuals that attacked you." Starlight asking
"It seems like ending up in this universe has slowed me down so I can't seem to get fast enough to get home. I'll help in any way I can. Where is that harsh British guy that was here?" Barry asks what happened to Butcher.
"Butcher, yeah, he is an acquired taste. He left because he didn't trust you, and the rest of the boys understand that you're probably our best bet against the seven. He has a mad plan with a virus that kills all supes." Starlight tries to explain why Butcher left.
"Oh, sorry, that sounds insane," Barry said, hearing about Butcher's crazy virus plan.
Don't be sorry. Butcher isn't trusting of superpowered people; it took him a while to trust me, and the only other person he trusts is Kimiko. Nearly every member of the boys has been hurt by a superpowered individual. We've lost people important to us. I used to be one of the seven until I realized how bad they are.
"Really, what made you realize they were bad?" Barry asks why Starlight left the Seven
"I met Hughie. I thought he was lying at first. I was mad when I found out that he was using me to get info on the Seven, but then I found out about compound V, the drug the company Vought made that is in charge of the Seven. It's what gives them superpowers; they inject us with it when we're babies. At first, I remained a part of the Seven to protect Hughie, but I couldn't handle hiding from all the bad things Homelander had done. Then I joined the Boys." Starlight explained her story to Barry.
"That's messed up, so what do we do now?" Barry asks Starlight what the plan is.
"I honestly don't know, but I think your speed will be helpful against Homelander.