Other sensations fought their way in. For the first split-second it had felt as if Steve were thrown. Then instead, he was sharply yanked backwards by something tied around his waist. He flew through the air to slam into a mercifully padded wall, and then dropped bonelessly to a slanted and similarly soft floor, where he lay panting for a moment.

Before he even opened his eyes, Steve could tell that something was terribly wrong. He'd had far worse impacts than this before. He'd jumped from moving trains and fallen ten stories to land on the marble floor of the Triskelion lobby – and in each case, he'd been able to hop to his feet almost immediately and continue fighting. Now, after what couldn't have been more than twenty or thirty feet, his head was spinning and he couldn't catch his breath. It felt as if all the life had been drained out of him.

What had Loki done? And who was applauding it?

When his head stopped spinning, Steve found he was lying face-down on the floor, which was covered with gray padding decorated in rows of black x's and triangles. Behind him it curved up into the wall he'd just hit, as if the whole thing were part of a single big cylindrical structure, but instead of going all the way around it stopped about twelve feet up. Overhead was a warehouse ceiling, all metal girders and banks of brilliant lights.

On Steve's left was a man he did not know – he was about thirty, with dark skin and short dreadlocks, and wearing sweatpants and a t-shirt with the NASA logo on it. A cord extended from the back of his shirt to a hole in the padded wall, and this was reeling and unreeling as he got to his feet.

On Steve's right was Natasha, wearing a turquoise blue jumpsuit with a number of embroidered patches sewn on each side of the front zipper. She was still on her hands and knees, but all her muscles were coiled to react immediately if necessary, and her eyes were darting bak and forth as she looked around.

In front of them, the padded curve ended five or six feet away, and beyond that were two large film cameras aimed at them, more dazzlingly bright lights and silky white photographic reflectors, and a whole row of strangers in street clothes. All of these were grinning and most of them still clapping, and one of the camera operators was pumping his arm in the air.

The man on Steve's left grabbed his arm to help him up. "You okay?" he asked.

"I don't know," Steve admitted.

A man stepped forward out of the little crowd. He was in his late sixties or early seventies, with dusty-blond hair and a beard going gray, and a deep crease in between his eyebrows. He was clapping, too, and smiling brightly.

"Much better," he said in a British accent. "Much better!"

"I told you!" The man in the NASA shirt beamed and clapped Steve on the shoulder. "The secret is don't tense up."

The bearded man came up and shook Steve's hand, then the black man's, then Natasha's. "Wonderful," he said. "Now that we've got that, we can leave the rest for the stunt people. Let's break for lunch. Maddy!" He looked over his shoulder at a woman with several tattoos decorating her shaved head. "Do you have those revisions?"

Maddy held up a manila folder.

"Good." The bearded man nodded. "Let's look over those, and I'd like to see everybody back in wardrobe by two o'clock. Now all of you, get out of here."

The lights started going out, leaving Steve, who'd been looking right into them, seeing spots. Some of the strangers left the room immediately. Others began taking equipment apart, and a woman came up to unhook the lines attached to Steve's, Natasha's, and the other man's clothing. Steve still didn't feel right. He was all sweaty and weak. It was almost like being that asthmatic kid in Brooklyn again, only it wasn't, because he was still tall, could still breathe deeply, could still tell the difference between red and green. What was wrong with him?

He looked at Nat. She looked back, not bothering to hide the fact that she was as confused as he. That was even worse. Things were bad when even Natasha didn't know what was going on.

The man with the beard had walked away now, and multiple conversations had begun. Counting on those and the sound of moving cameras and lights to cover his words, Steve said, "Natasha?"

"Yeah?" Nat asked. Her jumpsuit, he noticed, had the name Залётина – Zalyotina – embroidered on the pocket. Several of the badges also had Russian text on them, around motifs of rockets and space stations.

"What the hell was that?" asked Steve.

There was a brief pause in which Nat looked around again. "I do not know," she admitted.

"We're definitely not in Kansas anymore," Steve observed.

"We were never in Kansas to begin with," she replied.

Steve blinked. "Have you really not seen The Wizard of Oz?" After she'd made him watch all those ridiculous fantasy and sci-fi movies from the eighties?

"Of course I've seen The Wizard of Oz," said Nat. "I'm being a jerk about it because you said that before I could think of something more obscure."

The name Zalyotina had given Steve a moment of doubt whether this woman was indeed Natasha – that comment washed it away. "Okay," he said. "So… we're on a movie set." That much he could tell. Steve had been on movie sets before.

"I know we're on a movie set," said Nat. "I'm surprised you haven't started punching everybody in sight yet."

"I can't punch anybody right now," said Steve. "I feel terrible. Like I haven't slept in weeks." How long had it been since he'd felt this bad? Certainly not since he'd awakened in SHIELD's fake hospital room after seventy years in the ice. When he'd been injured after the helicarrier crash in Washington that had hurt, but he hadn't felt dulled like this.

"Good," said Nat, entirely without sympathy. "Try to keep a lid on the punch everybody instinct. These people aren't a threat to us."

A hand grabbed Steve's arm. A word was also spoken, but Steve didn't hear what it was, because he drowned it out with his own holler of surprise. He spun around and dropped into a fighting stance – his reflexes were slower than normal, but it was good to know they still worked. Nat jumped, as well, but they were not being attacked. It was just the black man in the NASA shirt, who seemed as startled by Steve's reaction as Steve had been by his touch.

He held up his hands and took a couple of steps back. "Didn't mean to scare you," he said. "Are you sure you're okay?"

Steve straightened up again, cautiously. His heart felt like it was going to pound its way right through his ribs. He couldn't remember the last time it had beat like that. The medics at SHIELD had told him he had the lowest resting heart rate of any human being. "I'm fine," he managed.

"Yeah." Natasha, too, was taking deep breaths. "Fine."

"Great," said the other man. "Come on, let's eat, huh?"

"Eat." Steve nodded. He was hungry, but Steve was always hungry, so it was a sensation he usually just tuned out. "Good idea."

Most of the original crowd had left the room by now and new people were arriving, setting up cameras and reflectors where the previous occupants had taken them down. Among them were three with the same haircuts and clothing as Steve, Nat, and their as-yet-unidentified co-star: a black man with short dreadlocks, wearing a NASA shirt; a woman with a blonde bob, in a blue jumpsuit; and a tall man with brown hair and beard stubble, in a UC Berkeley sweatshirt. They were waiting for their counterparts to leave the set.

"Sorry," Steve told them.

Nat took his arm. "Come on, guys," she said brightly. "I'm starved!"

They followed the other man down a short hallway and out a door into blinding sunlight. Steve's eyes were as slow to react as the rest of him, but once he could stop squinting he found they were in a parking lot outside a big white building with an arched roof, which looked like it could be an aircraft hangar but instead had the words Studio 6 painted on the side in large red letters. A few palm trees were visible above the roof, growing on the other side of the lot. Four metal steps led down to the parking lot, where several huge RV trailers were lined up – but rather than returning to those, the cast and crew had gathered around a catering truck that was serving Vietnamese submarine sandwiches. People were unfolding lawn chairs and passing around sodas and bottled water. Beyond the parking lot was a highway, with a green sign directing people to a turnoff that led to the Los Angeles city centre.

The tattooed woman named Maddy was handing out packets of pages. She pulled a set out of her folder and gave them to the man in the NASA shirt.

"Glover," she said.

"Thank you," he accepted it, and flipped it open for a look as he went to pick up his sandwich.

"Johansson." Maddy gave some pages to Nat.

Nat accepted them without comment.

"Evans." The third set was for Steve.

"Thanks," said Steve. He looked down at the cover – it bore a scene and revision number, and a line indicating that this copy belonged to somebody named either Chris Evans or Matt Rankin. When he opened it, he found Rankin's lines highlighted. Other characters, including Zalyotina, were participating in a conversation that sounded, what with mentions of oxygen levels and contacting Earth, as if it were happening on a spacecraft.

"Oh, and Donny," Maddy added, talking to the man in the NASA shirt. "Your friend at real-life NASA called. Hyperspace geometry girl."

Donny immediately lowered his script pages and pulled his phone out of his back pocket. "You mean Kevin?" he asked. "Thanks. I'll give her a call."

Although even his thinking felt slow, Steve was now beginning to come up with a theory. They knew that the tesseract was able to open wormholes, moving objects and people around in space at will. Whatever Loki had done, it had apparently caused Steve and Natasha to switch places with the actors making this movie – actors who looked creepily just like them, it seemed, since nobody had noticed the substitution. Thor and Loki were probably around here somewhere, too, just not in the immediate vicinity. What about the tesseract itself? Was it here, or still in the museum in Norway?

He looked at Natasha, who was pretending to read her script. She caught his eye, and nodded. They had to get out of here and get back to their mission, but they had to do it carefully. If they were on American soil, they could not afford to identify themselves. That would land them in prison.

"Okay," Nat announced, "there's been a big mistake here."

People looked up at her. Steve frowned – what was she going to do? She couldn't possibly just tell everybody who they really were, could she?

"What kind of mistake?" asked the bearded man.

"This." Nat thrust the script in his face. "This is not Russian."

"It's not?" He frowned. "We had a guy double-check it…"

"Well, was his name Google Translate?" Nat asked. "Because I guess yeah, it's technically Russian, but nobody talks like this!"

The man looked over at Steve, who considered a couple of options and then just shrugged. Nat knew what she was doing – he would just let her handle it.

"Why didn't you bring that up at the meeting yesterday?" the bearded man asked her.

"It slipped my mind," said Nat. "My shovel wasn't big enough for all the bullshit."

"Well, does it really matter?" he tried. "They'll dub the movie before showing it in Russia, anyway."

"What about Russian people living in the US?" Nat asked, arms folded across her chest. "I guess it's okay if we sound like idiots to them?"

He sighed heavily. "All right, I'll find somebody else to look at it. In the mean time…" he turned to Maddy. "I guess we need to figure out how we can use this afternoon. See what the second unit's up to. I've… I've gotta call the producer." He started taking back the pages his assistant had handed out, pausing to look Steve over. "You got any Russian?" he asked.

Steve tried to remember what little he knew. "Pivo, pozhaluysta," he offered. That was the first phrase Nat had taught him. It meant one beer, please.

It took a moment, but the man chuckled. "At least somebody around here has a sense of humour," he observed, and glanced back at Nat with a sigh. "Matt Damon said she was a pleasure to work with," he muttered.

Steve didn't know who Matt Damon was or why the name made him think of Asgard. "Well, that's just his opinion, isn't it?" he asked.

"Yeah." The bearded man sighed. He motioned for Maddy to follow, and they headed back up the steps into the studio building.

Nat took two sandwiches from the catering truck and gave one to Steve. "I will be in my trailer if anyone needs me," she declared grandly.

Donny frowned. "You don't have a trailer," he said. "You go home."

"Then I'll be in his trailer," Nat decided, looping her arm through Steve's.

Steve was amused in spite of himself as she dragged him away. "Well done," he murmured to her.

"I don't get to do full-tilt diva very often," she replied with a smile. "That's usually Stark's job."

"You just enjoy watching people who hate you have to put up with you anyway," Steve said. He'd done some of that during the war, showing up the generals and politicians who hated how this musclebound fool got all the attention. It did make him feel good.

"Everybody enjoys that," Nat said. "It's the evil queen in all of us." She chose one of the RVs at apparent random, and grabbed the door handle. "This one's yours."

"No, it's not," said Steve. The sign on the door bore the same name as had been highlighted on the front of his script: Chris Evans. It was a very nondescript name, Steve thought, like John Smith. Or, for that matter, Steve Rogers.

"Considering that Mr. Evans is probably picking himself out of the remains of the Museum of Cultural History in Oslo right now, I think he's got other things to worry about besides who's in his trailer," said Nat. "You can tell him we borrowed it, if that makes you feel better."

"I'll do that," Steve promised.

Natasha opened the door.

The first thing Steve saw was the dog, which had stood up on its hind legs to rest its paws against the inner screen. When Nat opened that second door to climb the steps and go inside, the dog bounced out past her to greet Steve. It was a floppy-eared, brown and white animal of indeterminate breed, and like most of its kind it seemed to have recognized Steve immediately as a dog lover. He knelt down to rubs its head and neck, and the dog wagged its tail and lolled its tongue out happily.

"Hi, there, boy," said Steve. He held out a hand for the dog to sniff. It licked his fingers, and with his other hand, Steve found its collar and tag. "Dodger," he read. "Nice to meet you, Dodger. Did somebody leave you here all alone?"

"Steve!" Natasha called from inside. "Come and take a look at this."

"Coming," Steve replied. He straightened up and gave Dodger's head a few more pats. If this were Chris Evans' dog, he thought, somebody was going to have to take care of it until its owner returned. Evans might be badly injured, or even under arrest. If he looked so much like Steve that nobody on this end had noticed the two switching places, right now he was probably telling a SWAT team that he wasn't Captain America. They weren't going to believe him.

With Dodger following close behind, hoping for more affection, Steve climbed the two steps into the trailer. The first room was a kitchen that was practically the size of Steve's entire apartment in 1940's Brooklyn, and it was a mess, with dishes in the sink and half a bowl of cereal uneaten on the table. Script pages were scattered around, and books and magazines on the American space program – but the first thing to really catch Steve's eye were the photographs taped to the cupboards. Some of these were of strangers, but many appeared to have Steve himself in them. If that were Chris Evans then yes, the resemblance was absolutely uncanny.

Some of the pictures were probably of Evans' family and friends. Others were perhaps from his movies. There was a photo of Evans standing next to an astonishingly tall man, perhaps a basketball player, both of them smiling. Another showed Evans bundled up against winter cold and looking like he'd just been beaten black and blue, but beaming as he posed with a teenage boy and a very schoolmarm-ish looking woman. There was, of all things, one of those ridiculous Doritos bags Stark had found so funny, framed on the wall as if it were a work of art.

Then Steve's stomach felt like it tied itself in a knot, as he began finding pictures of people he knew.

There was one of himself, Natasha, and Sam in street clothes, grinning and laughing. Worse, there was one of Steve, Bucky, and Peggy in uniform, leaning on the counter of that café in northern Italy in 1944 – where had some actor gotten that? Another was of Peggy making a face and pointing at a smiling Steve, both of them with twenty-first century clothing and haircuts, and looking directly into the camera. Yet another was of Steve, Stark, and T'Challa in suits and ties, with their arms around each other's shoulders like they were all best buddies. Steve didn't remember any of those pictures being taken. Some of them could not possibly have been taken, because the people in them were dead!

"Steve!" Natasha repeated.

"Nat, have you seen this?" Steve asked. Whatever she was calling him for, it couldn't possibly be as distressing as what he'd just found.

"Steve," she insisted, "have you seen this?"

When Steve tore his eyes away from the impossible photographs, he found Nat in the living room, at the front of the trailer. This was built around a fake fireplace that was really just a television screen playing a video of burning logs. Steve had never understood the point of such a thing, since it didn't keep anybody warm and couldn't be cooked on in an emergency, but there it was – and hanging above it were three framed movie posters.

These were done in what Steve recognized as an old-fashioned style by the standards of the 2010s. Modern posters tended to go in for teal and orange and a lot of photoshop filters. These were in watercolours, and were for separate but related films: Captain America: the First Avenger;Captain America: the Winter Soldier; and Captain America: Civil War. Each bore a list of actors' names, but the portraits were of people Steve knew. There was himself, Peggy, Bucky, Natasha, Sam, Stark… even Pearce and the Red Skull.

There had been Captain America films, of course. There were the ones Steve himself had been in, and then there'd been a couple more made by Howard's Stark Pictures in the late forties and early fifties, with Burt Lancaster and Ronald Reagan. There'd also been the two terrible made-for-TV movies from the eighties, in which Steve had been played by a guy who looked like his name ought to be Bolt Vanderhuge or something and who was, if possible, a worse actor than Steve himself.

The last few years had produced more Avengers-themed movies, as well. There'd been that one with Eric Bana as Dr. Banner, and the Battle of New York movie The Tower, which everybody seemed to have hated except for Dr. Foster's friend Darcy. The team had watched those, and had a good laugh at them. These were different. The faces were too perfect, and the titles suggested events uncomfortably close to the last several years of Steve's life. Anybody making movies about that was doing so without his permission.

"Those… aren't real movies, are they?" asked Steve, taking in the lists of names on each. He didn't recognize any of them except for the one from the trailer door: Chris Evans, his doppelgänger.

"They're not real movies in Kansas," said Natasha thoughtfully.

Steve turned his head to look at her, and found her in her 'thinking' pose, head cocked and brow creased. After a moment, she caught his eye, and took a deep breath.

"This is going to sound weird," she warned him.

"Weird? What's weird?" asked Steve. "We were just in Oslo looking for an alien who thinks he's a god and now we're making a movie. I don't know what weird is anymore. Tell me."

She didn't, though. Instead she stood there thinking a moment longer, then looked around the room. "Find me a computer or cell phone," she said. "I want to try something."

They searched the living room, which was tidier than the kitchen but only slightly, with Dodger the dog doing his best to help and mostly getting in the way. Underneath a pile of magazines Steve found a small laptop. When he turned it on a password screen popped up, but Nat got them past that easily, and Steve sat down on the ottoman and brought up Google.

"All right, what am I looking for?" he asked.

"Museum of cultural history explosion," Nat said, leaning on his shoulder to watch.

Steve entered the terms, slowly – SHIELD had gotten him lessons in touch-typing, but right now his fingers, like everything else, were clumsier than normal. The search engine thought for a moment, then presented a list of results.

To Steve's surprise, none of them were about what had just happened in Oslo. Never mind that the actual explosion had been less than an hour ago, in this age of instant communication and constant media presence, an event like that ought to be all over the news already. Instead, the first page of links was mostly articles about the Maritime Museum of the Atlantic in Halifax, Nova Scotia, which was being taken to task for neglecting black history.

"Try Avengers in Oslo," Nat suggested.

Steve tried it, and read off the first result that came up. "Oslo – Marvel Cinematic Universe Wiki," he said, and clicked on the link.

The article that came up was in white text on a black background, surrounded by ads, and it was very brief. The first paragraph discussed the paganist riots, which were something Steve could remember hearing about, although he'd been busy elsewhere at the time. The second part of the article was about Stark's visit to the NEXUS, and it quoted a conversation Steve remembered having with Stark, Banner, and Fury about Ultron's attempts to launch nuclear weapons. The men's names were all highlighted in blue – they were links to other pages. Steve licked his lips, then clicked on his own.

Nat leaned a little further forward, and this time it was she who started reading aloud. "Captain America is a fictional character appearing in American comic books published by Marvel Comics…" she said.

"What?" Steve interrupted. "Fictional?"

"Scroll down," said Nat, and when he didn't, she put a finger on the touchpad and did so herself. "Here we are! In Other Media. Actor Chris Evans portrays Steve Rogers in the Marvel Cinematic Universe Films Captain America: the First Avenger, The Avengers… yadda yadda yadda." She kept scrolling through a list rather longer than the three movies whose posters were on the wall.

"What?" Steve repeated. When he'd first awakened back in 2012, he'd learned that a lot of people did assume Captain America was a fictional character – a mascot invented for comics and old films as an embodiment of the optimistic allied war effort. Five years later, after Steve had been on the news, the Ellen Degeneres show, and that stupid Doritos bag, they ought to know better. Wikipedia certainly ought to know better.

"I was right," Nat said, sounding uncharacteristically surprised by it. "Huh."

"What were you right about?" Steve asked. "What's going on? Whatever it is, it can't possibly be any weirder than this is already, so just tell me."

Nat reached over his shoulder and clicked on one of the movie titles, apparently just out of curiosity. "Are you familiar with the idea of parallel universes?" she asked.

Steve had heard the phrase. It was something Stark and Banner occasionally talked about, but he had only a very vague understanding of the concept, garnered mostly from movies and television. "That's where there's an alternate world where things happened differently, and it somehow exists at the same time and place as our world, but we can't get there."

"Right," said Natasha. "Supposedly there's an infinite number of them, where all possibilities happen. There's a world where we lost in New York and Loki now rules the planet, there's a world where Ultron destroyed the earth…"

"If you're trying to make me feel better, it's not working," Steve pointed out. "We're in another universe?" Could the tesseract do that? Well, if this were actually happening, then yes, evidently it could.

"Loki said he would find another world to rule," said Nat. She found the Cast section of the article on The Avengers, and grabbed a piece of paper and a pen to start writing down the names. "I figured he was talking about an alien planet."

"I didn't stop to think about it," said Steve – though if he had, he would probably have come to the same conclusion. "He went to a universe where we're fictional, so we can't stop him from taking over?" Was that what he'd meant by where my enemies cannot touch me? In that case, though, wouldn't Loki himself be fiction, too? How did the people of this world know what to put in their movies, if those events had never happened here?

"Maybe. Maybe we all ended up here by accident when Thor broke the rune stone," said Nat. "So if you and I are in the place of the actors who played us in these movies… although I don't know why they'd name the movies after you when I'm the one who does all the hard stuff…"

"Thanks, Nat, that means a lot," said Steve. He could guess where she'd been going with the first part of that statement, though. "If we're here, we can assume that Thor and Loki must be, also, while the Steve and Natasha from this world… I mean…" he looked up at the central poster. "I mean Chris Evans and Scarlett Johansson…"

"They must be in our world," Nat agreed.

Steve had already figured that, but now he started seriously contemplating what it would actually mean. "Getting arrested for breaking into the Museum of Cultural History in Oslo," he said.

"And then handed over to the World Security Council for taking on a supervillain without the permission of the Norwegian government, in non-compliance with the Sokovia Accords," Nat agreed with a grimace.

"All while they insist that they're not Captain America and the Black Widow, they just play them in the movies!" Steve groaned. This was a very bad situation indeed. "All right, how do we fix it?"

"I don't know," Natasha said, "but I know who to ask."