It has been a while since their last encounter with the Burning Man also known as Ronnie Raymond and they got a report saying he attacked someone the night before and they now know he can't be left alone anymore.

"Well, it appears letting Ronnie roam free is no longer an option." Wells says as they're starting a search for him.

"He's not even Ronnie anymore." Caitlin states while searching. "He's Martin Stein walking around in Ronnie's body, like a vampire." She states.

"I'd think of it more like Invasion of the Body Snatchers, personally." Peter states remembering watching the movie with May one night when he was younger."is there a reason that Stein's brain is in control of Ronnie's body, not the other way around?" Barry asks anyone.

"Simple Darwinism, is suspect." Wells theorizes. "A brand new organism will select the strongest parts of itself in order to survive. Survival of the fittest. In this case being, Ronnie's body, steins mind." He explains to them and they understand mostly.

"In any event, he badly hurt an innocent man, and we have hunted metahuman for less." Wells states and looks to Caitlin. "Caitlin, we need to know you're onboard with this." He explains to her and she is.

"How do you suppose we find him?" Caitlin asks Wells. "Quentin Quale, the scientist that Ronnie attacked, he's a former colleague of Martian Stein. If Martin is indeed in control of Ronnie's body, he may be trying to figure out what exactly is happening to him."

"What do we know about him?" Barry asks them. "I mean, I don't know what Stein looks like." He asks and Peter quickly pulls up a photo of him.

"Stein actually visited Mercury labs a while back. Saw what I was doing with the Symbiote before it possessed me and saw it interesting." Peter explains how he knows him and Barry saw his picture and remembers he actually met him on the day of the particle accelerator explosion.

-

They decide to ask Martian's wife Clarissa if she knows anything of what's going on. "Of course I've heard of S.T.A.R. Labs. Martin was always vocal about the competition." Clarissa explains to Barry as the others look around their home for any leads.

"S.T.A.R. Labs is actually helping the CCPD looking into your husband's disappearance, mrs. Stein." Barry tells her.

"Oh, please. Call me Clarissa." She insists while Wells looks at Stein's achievements.

"The Conway Prize for scientific advancements." Wells reads looking at the awards. "I'd always hoped to win one of these myself. Oh, and look at that. He won it three times." Well states jokingly.

"Takes a special kind of person to make dr. Wells jealous." Barry says to Clarissa. "Well, Martin had a talent for making people jealous." Clarissa tells him.

"And you haven't heard from your husband since he disappeared?" Peter asks her. "No." She explains.

Barry then asks if he can show her a photo of Ronnie and she recognizes him and he's been following her. They believe that they have more than enough and leave her alone.

"So it appears Martian Stein and Ronnie Raymond have something in common besides sharing a body. They both feel the need to protect the women they love." Wells puts together as they're leaving Clarissa's driveway.

"She said she feels like she's being watched. What if she's being watched by him?...them? Is it they?" Peter wonders to how you refer to two people becoming one.

"Well, then, this has all the makings of a stakeout." Wells states. "But Barry has a date tonight." Caitlin tells them and Barry offers to cancel.

"No, you should go, man. I can hang out and wait." Peter tells him. "I mean, I beat a man who could blast electricity from everywhere, a psycho hunter and a guy with four mechanical limbs. I can handle my best friend's body with the mind of an old colleague." He tells them and Barry is okay with that and they promise if they need him, they'll call.

-

That night, they're in the S.T.A.R. Labs van keeping an eye out for Ronnie. Caitlin is in the driver seat while Wells is in the passenger side and Peter is in the back with his suit on but has the mask off since theirs no need for it yet.

"Want some of my fries?" Wells offers them and Peter takes some to keep his strength up for Ronnie.

"Why would he come back here?" Caitlin wonders not entirely understanding why Stein would risk it.

"Because this is his home." Wells states and that confuses them. "I don't mean the actual house. I mean Clarissa. She's his home." He explains to them. "You know, where we feel safe. Where we feel loved."

Just a second later the Burning man comes flying in and Peter grabs his mask ready for a fight. RonnieStein is walking around the house when Peter comes swinging in with his mask this time.

"Professor Stein, I'm not here to hurt you." Peter tells him while walking towards them/him. "And I know you don't want to hurt anyone, so please don't..." he gets interrupted when their hands and head burst into flames. "Flame on." Peter finishes before dodging a blast from him.

Peter quickly shoots out a web and pulls Ronnie to him and tries holding him down. RonnieStein just burns his hands again and starts flying and Peter grabs on for dear life.

"I know you probably don't know this, but ironically I'm afraid of heights." Peter jokes as he sees the S.T.A.R. Labs van following them trying to keep up. RonnieStein just flies close to the ground and tries doping Peter, but Peter uses the ground to his advantage and attaches another web to RonnieStein and they go tumbling down the street. As Peter's getting up, he sees RonnieStein getting ready to roast him when Caitlin comes out of the van screaming to Ronnie and they take off.

"Note to self, never get on Ronnie's badside." Peter quips and feels something might either be broken or burnt and Caitlin helps him up. "Oh, on the plus side, I was able to drop a spider-tracer on him." Peter says and Caitlin is happy they can at least keep their eyes on him now.

-

The next day they take Clarissa to see Martin and find him under the Central City highway. "Looks like your tracker worked, Peter." Caitlin says and RonnieStein tries walking away.

"Professor Stein?" Caitlin calls out. "I told you to stay away from me." RonnieStein reminds them as he keeps walking.

"And I will, but there's someone else who wants to talk to you." Caitlin explains and Clarissa walks ahead closer to him.

"Martin?" She calls out and he stops to see her. "Do you know who I am?" She asks him.

"Clarissa." RonnieStein says and she's surprised.

"Is it really you?" Clarissa asks him. "I don't know. I hear the other inside of me." He explains referring to Ronnie. "He wants to go home to them." He says looking to Caitlin and Peter. "But we can't. I want to be me again."

"Martin...what's my favorite color?" Clarissa asks to make sure it truly is her husband.

"You could never decide, so you chose stripes." He answers and she knows it's him. "You shouldn't see me like this." He tells her and she is happy to see that he's alive.

"I see you. I see you, Martin." She states. "These people can help you. Please let them." Clarissa begs Martian and he agrees to let them this time.

-

"Well, we got him. Them. They. You see what I mean?" Peter asks them seeing he doesn't know what to say. "Well, what do we do with them now?" Barry asks them.

"Well, Stein clearly thinks he can separate himself from Ronnie's body using nuclear fission." Wells explains the plan. "Is it possible? Theoretically. But splitting an atom and splitting a man are two very different things."

They all look to see RonnieStein join them in normal clothing and his hair is cut short. Peter and Caitlin just look shocked that he looks exactly like nothing happened but they forget that there's someone else in control. "I don't suppose it's necessary to point out you're all staring?" RonnieStein asks them and they stop.

"Our apologies." Wells apologizes. "It is remarkable. I feel clearer than I have since the accident." RonnieStein tells them while looking around the labs. "What did you give me?" RonnieStein asks Wells.

"A cocktail or anti-psychotics, depressants, and mood stabilizers." Wells answers him. "The same formula used to treat dissociative identity disorder."

"We'd like to run some tests on you, if you don't mind." Caitlin asks him. "Of course not, dr. Snow." RonnieStein tells her and Peter still finds this weird and Barry gets a call and goes to take it.

Peter was taking a few tests he knew how to work on so Caitlin could clear her head a little. "You comfortable?" Peter asks RonnieStein. "A little warm." He answers.

"That isn't exactly strange for Ronnie, he usually says he runs warm a lot. I think it's because he's a hothead." Peter replies and gets a reading of 107 on the monitors. "Okay, that's hotter than his hotheadedness." Peter says after seeing it.

"So, how does this exactly work?" Peter asks curiously regarding their situation. "Is it like you can hear him in your head like a voice, or is it like you can see his memories?" Peter wonders.

"It's...more like I can feel him. But I occasionally have some memories." RonnieStein answers him. "Memories I know aren't mine. One strange one that constantly appears as much as a Hudson Falls memory." RonnieStein says and Peter knows that's where Ronnie proposed to Caitlin. "It seems to be like a bedroom of sorts. A bunch of what I believe to be Star Wars merchandise filling the room and a kid in red and blue crawling on the ceiling." RonnieStein describes the memory and Peter knows what that is.

"That's my bedroom when I was younger. You're describing the day Ronnie learned who I was hiding. The day he learned I was Spider-Man." Peter smiles thinking of the memory. "I just got home after spending the afternoon keeping the city safe and I came in through my window in my suit and I wasn't expecting him that day, but that's how he figured it out. He was the first to learn about it."

"Peter, we need to see you quickly." Caitlin tells him from the doorway. "I'll be back." Peter states and follows Caitlin to see Wells focused on the data.

"Ronnie's body is rejecting Stein's atoms like a host rejecting a parasite. The resulting instability is causing exothermic reaction." Sells tells them and they see his temperature is rising. "I worry if his temperature continues to rise, it'll set off a chain reaction."

"Are you saying he could go nuclear?" Peter asks Wells. "That's exactly what I'm saying." Wells tells him.

Meanwhile Cisco comes back after helping Joe find some blood at Barry's old childhood home to figure out who murdered his mother and runs into RonnieStein.

"Ronnie?" Cisco asks and remembers it's not him. "Martin Stein." Stein introduces himself to Cisco. "Cisco Ramon." Cisco says introducing himself as well.

"Your colleagues are in the next room not so subtly discussing my condition." RonnieStein tells him and Cisco goes to join them. "That's not freaky at all." He states sarcastically to the others.

"Thinking the same thing, man." Peter replies as they refocus on the situation. "It seems Ronnie's fight with Spider-Man has exacerbated the Firestorm matrix. It's unstable. Exponentially increasing the rate of fission inside his body." Wells explains to the team as they move to the cortex.

"How long does he have?" Caitlin asks Wells. "If his temple keeps rising at the current pace, no more than a couple of hours." He answes her.

"Then we should figure out a way to separate them, right?" Peter questions hoping there's a way. "Any attempt we make to separate the two of them could be catastrophic, a nuclear explosion. And a nuclear explosion of this magnitude would level the city. Unless...we find a way fast enough." Wells explains. "And I might have something, stay here." He tells them and leaves to get the tachyon enhancer from his suit.

"Gideon, could the tachyon enhancer prototype be converted into a quantum splicer?" Wells asks Gideon. "Theoretically, But I must warn you, dr. Wells, converting the tachyon prototype will delay your timetable." She warns him.

"There's not going to be a timetable if Central City goes up in a mushroom cloud." Wells states and starts getting to work and leaves to explain to the others.

"I'll get professor Stein." Barry offers and before he could leave Cisco comes up to them. "Looking for the professor?" He asks them. "Yeah, he's gone." He states and they don't know where he could've gone.

Peter, Cisco, Wells gets to work on the quantum splicer to save them as Caitlin locates them. "I found Stein, he's in the badlands." She tells them and sees why he chose the location. "Middle of nowhere, 30 miles outside Central City."

"It's the minimum safety distance for a nuclear explosion." Peter states and realizes what he's doing.

"He's sacrificing himself." Cisco states seeing it also. "How much time does he have left?" Barry asks them.

"Twelve minutes maybe." Cisco informs him and they finish the splicer. "Will this work to separate them?" Caitlin asks since none of them have any idea if this will work.

"Well know in twelve minutes." Wells says and hands it to Barry. "Now, Barry, even you can't outrun a nuclear blast, so you get this device to Professor Stein, and get out of there as fast as you can." He tells him and Peter grabs his mask.

"What are you thinking?" Barry asks him. "What, you think I'm letting you go alone? That's my best friend's life on the line. Besides, if I get caught in the explosion I'm already radioactive thanks to the spider bite so I'll be safe. Besides I know how to operate the splicer, so let's go." Peter explains and Barry sees he's right and they go speeding off.

As soon as they leave a test result comes from the computers regarding Cisco's test results for the blood at Barry's childhood home and he sees it's Barry's. But not childhood Barry, it was from Barry as an adult.

-

Out in the badlands, Barry and Peter come to a stop to see RonnieStein holding a gun to his own head ready to shoot. "Professor Stein!" Barry calls out as Peter regains his legs after that run. RonnieStein looks behind him to see them. "What are you doing here? You can't be here!" He scolds the heroes.

"Please, look we have a way of separating the two from each other." Peter says and moves closer to him. "We can stop the explosion and your deaths." Peter pleads to him and takes the enhancer. "This is designed to bombard your atoms with as much energy as they experienced in the accelerator explosion." Peter explains the plan and RonnieStein agrees to it as Peter attaches the device to his chest.

"Looking forward to meeting you again, Professor." Peter says and activated the device and it wraps against his chest and they pray it works.

RonnieStein's body starts burning up and they see it's not working.

"We gotta go!!" Peter shouts knowing radiation won't kill him but the blast could and Barry grabs him and they speed off as RonnieStein blows in a huge mushroom cloud and they keep running.

-

Little did they know that the government actually heard about the detonation and is now sending someone to find him. Them. You know what I mean.