The three women from NASA got back into the elevator, and the doors closed on them with a rather uncomfortable finality. Steve only spent half a second staring at the brushed metal and wishing he could go with them, but even that was too long. He couldn't do that, not because of an injury or because of the limitations of a body without super-soldier serum, but merely because he could not be in two places at once. There were some things, even at the best of times, that he simply had to leave to others.

The rest of them had to find the building Ellen Ochoa had called Old Mission Control. There was a visitor's directory map in front of the remains of the dais that had supported the spacecraft model, so Thor and Loki stood guard while Steve and Nat cleaned the bits off it and examined the battered surface.

"Okay, we're here," said Steve, finding the red dot.

"And it says Old Mission Control is this building here." Nat put her own finger on the map, a couple of inches from his. "So we just need to cross this open area." She glanced towards the main doors. There was a courtyard with trees outside, with the top of another building visible above them. It was only maybe two hundred yards.

Of course it wouldn't be that easy. The sound of heavy footsteps through the ceiling overhead told them that the rest of the Chi'Tauri were on their way. Instinctively the group clustered together, with Nat and the Asgardians moving in front of the injured Steve as they all edged towards the doors, hoping to get there before the aliens cut them off, but knowing they probably wouldn't.

"It'll be up to you, brother," Thor said quietly. "You're the best-armed."

"I know," said Loki, hefting the plasma rifle. It was clearly very heavy – the Chi'Tauri soldier had waved it around like nothing, but Loki needed both arms. "We'll have to take them off-guard."

"We could do Get Help," Thor suggested.

Loki rolled his eyes and shook his head. "You wouldn't have the strength. Not in this body."

"I bet I could, at that," Thor said.

"We are not doing Get Help," Loki said firmly. "There is no need."

"What's Get Help?" asked Natasha.

Thor began to explain. "It's a ploy we used to…"

"If you don't stop talking I will shoot you," Loki interrupted.

One of the soldiers burst out of the stairwell into the room, and the first thing it saw was not the little group of humans moving towards the doors, but the smashed spacecraft model and its fallen comrade. Loki hefted his stolen plasma rifle and fired, but the weight of the weapon and his lack of familiarity with it got in the way, and he missed. Instead of hitting the Chi'Tauri, the bolt blew apart the rest of the model spacecraft and most of the carpeted pedestal it had been mounted on, and the element of surprise was lost.

He immediately lined up a second shot, but the soldier did something with its own weapon, and there was a flash of glittering pink in the air around it. When Loki fired again, the shot was harmlessly absorbed by this force field.

Steve had no idea what the word Loki barked out might mean, but it probably wasn't something Queen Frigga would have approved of.

"Figure out how to turn that on," said Thor.

"What do you think I am trying to do?" Loki demanded, studying the weapon in his hands.

Steve used his now slightly bent crutch to drag over the dish from the remains of the model spacecraft. It had never been much of a shield in the first place, and now it was cracked and brittle on one side where it had been exposed to the liquid nitrogen, but it was psychologically helpful as they continued to limp towards the door. Why did a space centre need such a big lobby?

"They're going to fire again," Thor said, peeking around the edge. "Have you got it yet?"

"I am working on it," Loki told him.

"We are trying to save the world here! Can you two stop bickering?" Natasha asked.

"No!" the brothers replied, in perfect unison.

The alien took a shot at them. The bolt of plasma went right through the dish, burning a hole in it, and narrowly missed the back of Steve's head. The edges of the plastic cooled quickly, leaving them blackened and melted. Steve rubbed his scalp to make sure his hair wasn't on fire, then peeked through thehole and saw two Chi'Tauri now heading towards them.

"Here it is!" said Loki, and the same pink shimmer appeared around them. "Do you see," he asked Thor, "how much easier it is to do things when you're not thundering in my ear?"

It hadn't been a moment too soon. Another shot quickly followed the first, but was absorbed by the force field. Steve dropped the dish, and they began moving with more confidence.

"Return fire," Thor urged.

"It won't let me while the force field is on," said Loki. "It would absorb our own shots… obviously."

The front of the building was a set of big glass windows and doors. A stray shot from one of the Chi'Tauri helpfully shattered these for them, in the process taking out a pillar that Steve worried was probably structural. They stayed close to Loki, and stepped through one of the broken panes. Steve's limp was slowing them all down, but they couldn't leave him or turn back now. He wondered where the Chi'Tauri Commander was. Hopefully not chasing down escaped NASA employees.

"I see the vehicles!" said Natasha. "Over there, by the fountain!"

Steve looked. There they were, two of the alien air scooters floating gently side-by-side, just as they'd been in the parking lot outside the Canadian convention centre. Only a few more yards now. They were almost home free.

There was the sound of breaking glass above them, and the Chi'Tauri Commander leaped out a third-storey window. It landed on its feet in front of them and aimed its stafflike weapon at the group. Loki held up the plasma rifle as if to physically shield them with it. The Commander fired, and the pink field absorbed the blast, but it flickered and fizzed like an old television set. With a yelp of pain, Loki threw the rifle onto the grass. It lay there sparking and smoking. The staff weapon was far more powerful, and the force field from rifle couldn't take the blow more than once.

"Scatter!" Steve ordered. "Leave me, just get there!"

Thor and Natasha darted off in different directions. Thor simply made a wide circle to the left, back around to where the vehicles were, while Natasha took a more complicated, weaving route to the right, trying to be harder to hit. Steve, who could not run, had no choice but to stay where he was, leaning on that damned crutch. Easy prey – but if the Commander killed him, maybe the others could get away.

He wondered what would happen if he died. This actor, Chris Evans, would be stuck with Steve's body. Would he want to come back to this universe and resume his acting career, or would he be willing to stay in the other one and take over the role of Captain America in a much more literal sense? Neither seemed like a good idea.

Then he realized that Loki hadn't run. Instead, the god of mischief and lies stepped in between Steve and the Commander, calmly facing his enemy. The Chi'Tauri cocked its head and lowered the staff a little. It must have orders to take Loki alive.

"Really," said Loki, in a voice suggesting disgust but not surprise. "You call yourself a warrior, when you're standing here ready to kill an unarmed, injured man?"

Loki himself had shot the frozen Chi'Tauri a moment ago… but Steve supposed Loki had never pretended to be an honourable creature.

"You're not here for these insects," Loki said. "You're here for me. Going after them is a waste of time and resources – yours, and your master's."

Was Loki actually sacrificing himself to save Steve? That was ridiculous – and yet as Steve watched, astonished, Loki held up his arms on either side of himself. The right one was red, the sleeve of his jacket singed from when the plasma rifle had overloaded.

"I am unarmed," Loki said, "and I am sick of watching these useless mortals make fools of themselves. I assume you have my alternate captive. If you will allow me to take my body back before I confront Thanos, I will come with you willingly."

The Chi'Tauri commander stepped closer. Tom Hiddleston was a tall man, but the hulking alien loomed over him, looking as if it could crush him like an insect. "Two bodies," it rasped. "Thanos can kill you twice!"

Loki stood there a moment longer, straight-backed and defiant, then suddenly threw himself on top of Steve. From behind one of the Chi'Tauri flying vehicles ploughed into the Commander, literally sweeping the alien off its feet and throwing it into the doors of the building behind. The doors themselves were designed to open outwards, so the impact smashed their glass panes and broke one off its hinges, and that was apparently just a tiny bit more than the aging building could take. The façade sagged, then peeled off the front of the building like wallpaper to land with an immense crash of glass, concrete, and dust on the pavement in front. The other two Chi'Tauri, who'd been on their way out, were buried in the mess.

Thor brought the vehicle back around and reached to drag Steve up onto it. "That was almost Get Help!" he said.

"I approve!" Loki replied.

Natasha had the other vehicle. Loki climbed on behind her. Thor pulled back on the controls to gain altitude, and Steve put his arms around Thor's middle and held on tight as they climbed. Against his better judgment, he stole a glance down The three Chi'Tauri were picking themselves up out of the collapse, and Steve quickly turned away again as they raised their weapons.

"Far right!" Loki called. He and Natasha were flying next to Steve and Thor, and Loki reached up past Nat to punch a button on the control panel. The pink shimmer appeared around them. Thor did the same, just in time – moments later, plasma bolts were bouncing off the force fields.

Below them, the ground continued to spiral away until the aliens were lost among the trees, and Steve tightened his grip on Thor as much as his aching shoulders would allow. He felt terribly exposed, which may have been absurd for a man who routinely jumped out of planes with no parachute. This felt different, though – he was basically balancing on a flying surfboard, with nothing at all to keep him in place and no guarantee he'd land on his feet.

Hayley – and Peggy – had made fun of Steve's propensity for doing very dangerous things, but Steve had spent the last few years learning just what was and was not dangerous for him. He knew by now when he was likely to survive something, such as jumping out of the Triskelion elevator, and when he was not, such as crashing the Valkyrie. There was a time for self-sacrificing wanker-hood, and now was not it. Not when they had so much more to do today. And if there were no time for that there was definitely no time to slip and fall. He hoped Thor could still breathe.

The Leviathan passed overhead, and for a moment they were in its shadow. Steve looked up. He thought he'd remembered how big these things were, and it had looked big hovering over Houston in the newspaper photograph – but now that he was up close, its size astonished him all over again. How did this contraption stay in the air when it had nothing but those tiny fins, beating gently like the legs of an aquatic insect? He remembered Loki saying something about an anti-gravity field. Stark would probably be able to figure it out, but for some reason Stark had refused to work on any of the captured Chi'Tauri technology.

Steve wondered if the reason why not had anything to do with how the Leviathan looked horribly like a living thing. The teeth in front gave it the appearance of having a blind head, and its undulating body structure looked like a spine. The Chi'Tauri had built mechanical components into their own bodies to strengthen them. Had they also knitted biological features into their machiens? Or was this some kind of animal, perhaps a thing that had once swum in an alien ocean before the Chi'Tauri dragged it out and turned it into a war machine?

"Oh!" Natasha exclaimed.

"What?" asked Steve, but a moment later he found out, as the craft he and Thor were riding gave a sudden jolt and then slowed and steadied, as if being guided through the air by a giant, rock-solid invisible hand. Thor tried to move the steering control, but could not do it.

"Don't panic," said Loki. "The main computer is guiding us in to dock." His voice was calm, but Steve saw him re-arrange his hold on his fire extinguisher. Natasha and Thor had theirs, and Steve was still carrying one, too. They might all be about to need them.

Their vehicles separated and moved into line with opposite sides of the Leviathan, matching its speed and sinuous motion exactly as they drew closer and closer. There was plenty of space as they backed into the docking port, but Steve still instinctively pulled his arms in. Darkness closed in around them, and connectors shot out to hook into both sides of the vehicle. The Leviathan was still moving all around them, while in the middle of it they seemed to be sitting perfectly still.

There, Steve waited a moment for his eyes to adjust – another thing this body did slower than his own – but even then, there wasn't much to see. The walls were very close in around them, and overhead was a tunnel made of overlapping rings so that it could flex as the Leviathan flew. On one side of this was a set of rungs, very widely spaced by human standards but still obviously a ladder, that led up into the body of the craft.

"'Fist bump'?" asked Thor, holding up a hand. The inverted commas were audible around what he considered a quaint Midgardian expression.

"Sure. Okay." Steve completed the gesture, then looked up again and took a deep breath. "Here we go," he murmured, already seeing visions of those plates suddenly contracting to crush him to a bloody pulp.

Climbing was a difficult, disorienting experience, with the walls moving around them and the rungs designed for a creature with much bigger hands and a longer reach. Thor went first, struggling for a moment before he managed to get in time with the rhythm of the sinuous craft. Steve tried to copy his timing as he followed. His bad ankle continued to be very upset about his insistence on using it and threatened to collapse out from under him at any moment, but Steve didn't trust himself to maintain his hold with only one foot on the ladder. He'd managed to handle the pain of coughing with broken ribs when he'd had pertussis. He could grit his teeth, and handle this.

Thor made it to the top, and offered Steve a hand to help him up the last few feet. Then they tried to look around.

It was even darker up here, and very warm. Steve's hair stirred in a slight hot breeze that had an odd chemical smell to it, and there was the constant sound of things sliding against each other, making a variety of whispery or slippery noises as if voices were talking about them in the shadows. The first image that occurred to Steve was of being inside a large, sleeping animal. He squinted, trying to see something besides the occasional soft glint off a surface in motion, and then there was a flare of bright light off to his right.

It was Natasha. She and Loki had climbed out of the tunnel across the hall, and she had turned on a small LED flashlight. Steve made eye contact with her, and they both nodded. So far, everybody was okay.

Now that there was light Steve could assess the situation properly. Around them there was very little to be seen, besides the moving walls and some spaces that looked like they were designed to store weapons or equipment – these were empty. Then Natasha pointed the flashlight up, and Steve stopped breathing.

For a moment he wasn't sure what he was seeing, whether it was one creature or several or even which way up it was. Then his brain managed to sort out the parts, and he realized that the being hanging from the ceiling above them, and flexing with it as the Leviathan flew, could only be the Chi'Tauri Queen.

While her soldiers wore only very basic armor, the Queen was covered nearly from head to toe in grayish gold plates with a matte surface finished, interrupted by embossed silver and multicoloured gems worked into shapes that looked like intestines, or like squirming maggots – wiggly, segmented designs that suggested biology in the most repulsive way possible. It was obviously of luxurious make, far more decorative than that of the grunts, but still perfectly functional to protect its wearer in a fight.

Worse, that wearer was huge. Standing, she might have been twelve feet tall, with two legs like tree trunks and four arms, one pair above the others. She had four eyes, too, and was looking down at them from her cocoon on the ceiling, as surprised to see these intruders as they were to see her.

For a split second, nobody moved. Then the Queen reached down, and tried to grab Natasha.

Nat responded by pouring out the contents of the liquid nitrogen fire extinguisher. The Queen shrieked and snatched her hand back, steaming ice all over her gauntlet. Then she lashed out again, with the lower arm on the same side. She knocked the extinguisher out of Nat's hands and slammed her into the wall, while pulling her cocoon open with her other limbs and dropping to stand in front of them. The space inside the Leviathan was narrow and in constant motion, like being inside a heaving submarine, and she seemed to fill it entirely. She hissed at them through her skeletal teeth.

Thor turned Steve towards the bow and pushed him. "Go find the wormhole machine!" he ordered.

"But…" Steve began. He looked over at Natasha, who was picking herself up, shaking her head as if dazed. The flashlight was lying a yard away, and suddenly went out as the Queen's huge foot came down on it, covering the light.

"You were the one who told us to leave you behind on the ground," said Thor. "The rest of us will deal with the Queen, as we planned!"

Steve didn't want to go. He didn't want to leave Natasha behind, not after all the times when she had refused to leave him. Thor and Loki were not as strong as they were used to being, and they might not be able to handle this. But the whole reason they'd planned it this way was because Steve was injured, which mean they were still more up to it than he was. It was too late to change his mind now.

So he turned and half-walked, half-crawled up the moving tunnel, like crawling up an animal's throat or through the middle of a machine with many moving parts, towards the front of the Leviathan. In the darkness he had to feel his way along, avoiding the holes on both sides of the floor that were meant for troops to climb in and out. The occasional faint glimmer of light showed him racks further up where they could store weapons. Some of these appeared to still have plasma rifles stowed in them. Steve looked back, but between the darkness and the constantly moving structure he could no longer see the others. He would just have to hope they could find more weapons on their own if they needed them.

Surely they would. They were smart and observant, and it had served the whole team well in the past. Steve couldn't do everything, even if he felt like he should.

He continued to stagger forward, his steps unsteady as the walls flexed and the ceiling and floor bowed up and down. How in the world had Stark managed to just fly right through this thing? Had he gotten his computers to chart him a safe course? Or had he just gritted his teeth and hoped for the best. Either way, Steve had a new respect for something that had been so quickly done and over with at the time.

Behind him were flashes of light, and the sound of plasma rifle fire. That was good, it meant they had found the weapons. It was followed, however, by a human sounding cry of pain that nearly stopped Steve dead in his tracks. He hesitated there a moment, then forced himself to keep going. If he looked back, he might catch the Leviathan as it moved in just the right way to let him see them. If he saw them and they were losing, he would want to turn around and help. He couldn't afford that.

At the very front of the Leviathan was the mouth, closed but with daylight seeping in around the teeth. On either side of that were two more of the flexible ladders. Steve dragged himself up the one on the right, and found himself in what he could only describe as the cockpit.

To Steve's left and right were a pair of semicircular alcoves, with multiple controls above and below a holographic view screen not unlike something Stark might have dreamed up. The screens showed an image of the buildings and trees below them, over which multiple small circles were swarming like flies. Those had to be for aiming gunnery turrets, Steve decided, or some equivalent. In between the alcoves was the main control area. It had a wide panel across the front, covered with buttons and switches and a two-handled steering device. Above was a big hologram showing the sky ahead, and several smaller ones on each side with other points of view, including one with a map of the stars.

That was a start. The wormhole machine had to be in here somewhere. This was where the pilots controlled everything else about the Leviathan's movement, so it made sense it would also be where they decided what universe they were in.

Steve was working his way down the main control panel, trying to decide if he could tell what anything on it did, when something crackled. The large view screen shrank and moved down to the side, while another expanded to fill the space. While the view ahead presumably came from some equivalent of a video camera, it was at first hard to tell what could be sending this one. It was a view inside a room with office chairs around a big wooden table. A group of humans, six or eight of them in business casual attire, were cowering in a corner. They'd pulled some of the chairs close around them into a makeshift barricade. The view darted back and forth, and then Steve noticed that the tip of a staff weapon was visible at the bottom edge of it. He was seeing what the Commander could see, transmitted via the biomechanics directly from its brain.

An arm reached out and grabbed a man from behind the barricade – an elderly, balding fellow with a bushy silver mustache and reading glasses hooked into the collar of his polo shirt. The other hostages tried to hold onto him, but the Commander dragged him out of their hands. The staff weapon came up and poked into the side of the man's head, and he covered his face, sobbing.

"Watch, Avengers!" said the rasping voice of the alien.

It was going to kill the hostages, Steve realized, a cold sweat breaking out on his brow and back. It was going to kill them in order to punish Steve and the others for interfering in their mission, and there was nothing he could do about it. He looked at the controls in front of him, wondering if there were some way to send a message, but he didn't know what any of these devices did. The only thing he recognized was the steering.

The structure of the Leviathan shook, as if something heavy were being thrown around inside it. Steve hoped that was the queen dying, and not one of the others being crushed to death.

He couldn't let the hostages die, though. What were his options? The Chi'Tauri would lose consciousness when their connection to the Queen was severed, but he had no idea how the fight was going and it might be going badly. The only other idea he had was to get back to the ground as fast as he could. Steve seized the steering handles. It took a great effort to get them to start moving, but once he'd overcome that initial resistance they seemed to work smoothly. He turned to the left and angled the Leviathan into a dive, heading for the building with the damaged front façade. Rooms could be seen open to the air, like cells in a beehive.

"Steve!" shouted Natasha.

He glanced down, and saw her climbing up into the cockpit next to him. There was blood in her hair and a big cut down one side of her face, with more blood staining her t-shirt. "What the hell are you doing now?" she demanded.

"They're going to kill the hostages!" he replied.

Nat probably would have had something to say in response to that, but then there was a crash, another cry, and Thor and Loki scrambled into the cockpit to join them. For a moment Steve was reassured to think that if they were running from the Queen, the entrances were not big enough to admit her. That thought was interrupted by a clunk and a grinding sound, and the back wall of the cockpit began to open.

Loki dropped the plasma rifle he was holding and grabbed a handhold in the wall, trying to force it closed again. Thor, his clothes half torn off and his chest covered in bloody scratches, joined him, but they were not strong enough. The Queen got one arm through, then another, and used her broad shoulders to force it open. Thor and Loki let go and dropped to the floor on either side.

"Freezing didn't work," said Steve. It wasn't even a question.

"She's got a personal force field," Nat told him. "Once she realized the nitrogen could hurt her she turned it on, and it can apparently deflect the spray. It's on her belt." As the Queen loomed up, Nat pointed to a big dark gem in the centre of her wide chain-link belt, which was shimmering pink to match the hint colour in the air around her.

"All right," said Steve, "somebody's gotta…"

"You gotta fly the damn ship," said Natasha. "Since you seem to think you can!"

Steve looked back up at the display, and his stomach dropped as he realized they were moments from hitting the building. He cranked the controls back again, and the Leviathan headed towards the sky. On the screen that represented what the Commander was seeing, there was a flash of motion, and the view turned to watch the Leviathan's tail pass by the blown-out wall at the far in the end of the room. They were still in there, Steve realized. There were people still in that building and he'd nearly rammed a Leviathan right through it.

"Give me a lift!" Nat ordered – and without giving Steve a chance to reply, she grabbed him by the collar and started climbing him.

"Ow!" he said.

"Sorry," she said, and found a handle in the ceiling, which she used to swing herself onto the Chi'Tauri Queen's shoulders.

Steve let go of the controls to turn and watch, but as soon as he did, the Leviathan began to lose altitude again. He grabbed the column to correct it, and realized that he was now stuck having to fly this thing. The initial resistance he'd overcome to change its course must have represented turning off some kind of autopilot, and he had no idea how to turn it back on.

The Queen's entire long torso was through the entrance, and she was trying to grab Loki and Thor. They'd backed up against the walls to avoid her, but there wasn't space. Loki had his plasma rifle and Thor a fire extinguisher, but with the force field active these were little more than clubs to swat at the questing fingers.

Nat did a somersault, and landed on the Queen's back. The alien reached up with a third arm to seize her around the middle, and held her upside down, snarling in her face. Her other arms continued to engage the Asgardians. One yanked the fire extinguisher out of Thor's hands. Another slammed Thor against a wall – and that left one more arm for Steve.

They were all trapped.