Hold Your Breath

SPOILERS: Do not read if you haven't yet seen Avengers: Age of Ultron!

Summary: Following the events of Sokovia and Ultron's demise, the Avengers help the remaining SHIELD agents get back on their feet and set up a new base in the heart of the Rocky Mountains. Inaccessible by plane, the heroes escort a convoy of SHIELD equipment and personnel through a tunnel ten miles long. Only, someone's beaten the convoy there and set up charges in the depths of the mountain along the tunnel walls. The Avengers face their most life-threatening mission yet, not in waves of aliens or a bugged AI, but in criminal sabotage with the weight of a mountain pressing down.

Chapter One:

Nat:

"Coulson was right. This is in the middle of nowhere."

Nat stared out the car window at the jagged mountains and the valleys diving far, far below. Steve gave a chuckle and said, "It's not nowhere, it's the Rockies."

"There aren't even any power lines, Steve. Power lines."

"So?" he said.

She turned to look at the soldier, his shield glinting faintly at his feet.

"I know SHIELD's high tech, but this new base still needs to run on some form of electricity."

He just snorted in amusement and turned to look out his own window. Nat pulled herself up using the driver's seat and leaned into the front of the SUV.

"How far, Carl?" Nat asked.

Carl, their driver, turned his head and said, "It's just through there," and nodded ahead to a tunnel. It was a dark maw leading into the belly of the mountain before them. An odd wave of apprehension swept over her, but she ignored it. Nat had to admit that the mountains were beautiful if nothing else. Their convoy had been driving through them all day, the new base inaccessible by plane. The Avengers were called in to help, mostly to protect the many, many, many weapons and equipment being shipped. After the entire Ultron fiasco, what was left of SHIELD needed a new base, somewhere they could start over and maybe get it right this time. This new base wasn't exactly new-an old relic from the WWII days, but Fury deemed it as good a place as any. And if Fury also saw fit for a bit of manual labor, then Thor, Steve, and Tony would be conveniently close. She sat back and gazed out the window where the earth seemed to bunch and fold in upon itself. The sun was just slightly to the left, a brilliant haze of gold slowly sinking behind the mountains. She looked forward to the tunnel and the mountain it was nestled in. A few SHIELD guards stood at the entrance, holding intimidating rifles and wearing stern faces. As the few vehicles in front of theirs slowed, the guards approached the windows and exchanged words. The convoy came to a stop. A flash of red and gold shot by Nat's window and Tony landed right beside the guard, the clank of his armor able to be heard even from this far away. The SHIELD agent jumped in surprise, turning to face Stark. The engineer's face plate was retracted and a broad grin was visible. He and the agent exchanged a few rather passionate words, but he continued to badger the man even as the SHIELD agent turned away. Steve shook his head slightly, a look of exasperation on his face.

"Can't act his age, can he?"

"Guess not," Nat replied.

After a moment, she nudged Steve's shoulder and said, "Hey, hold your breath."

"What?"

"Hold your breath when we go through the tunnel," she said with a crooked smirk.

"Why?" he asked, confusion twisting his brow.

"Because it's fun. See if you can make it through," she challenged.

Carl turned around from the front and said, "Good luck with that. It's at least ten miles straight through."

"Way to suck the fun out of everything Carl," Nat said.

At that point, the guard had shooed Tony off and dealt with the lead car of the convoy. The line of cars started up their trek again. Nat saw the flash of red disappear into the tunnel, and she pictured Tony mapping out the new base and hacking into the newborn computer system before it was even properly started up. The cars in front disappeared into the tunnel, their headlights and harsh yellow bulbs on the walls lighting the way. Then it was their turn, and despite Carl, Natasha held her breath. Steve turned to her and rolled his eyes when he realized what she was doing. She lost sight of his face as the car traveled into the tunnel, their SUV swallowed in darkness. Still, she held her breath and made it perhaps two minutes before the first bomb went off.

This should have been routine. This should have been routine. This should have been routine.It became a chant in Nat's head. She screamed out in surprise and gripped the back of Carl's seat in front of her. How could this have gone so south so quickly? The charges were still going off, sending out shock-waves that hit the car and shuddering booms so loud she could barely think. She heard brakes squealing from the other vehicles around them, and then the tunnel lights flickered off. The bombs kept up an incessant thunder, shaking Natasha to her very bones. Carl shouted out something unintelligible, and by their headlights, Nat could see rocks beginning to fall. And not a few pebbles, but boulders, huge chunks of earth and rock. She shouted again as one such rock fell through the front of the car, crushing Carl. The windows shattered and they came literally to a crashing stop, Nat flying into the back of Carl's seat.

"Nat!" Steve shouted, and distantly she heard the sound of seat belts ripping. "Are you alright? Nat? Nat!"

He grabbed her arms and pulled Nat around to look at her.

"I'm fine," she said. "Just a little dizzy."

He opened his mouth to respond but was cut off by another thundering boom, and something big hit the top of the car hard. Faster than Nat could comprehend, Steve ripped her seat belt off too and pushed her into the floorboard. She shouted in horror as the car's roof collapsed on Steve's back, trapping them beneath the mountain.

Tony:

Tony decided that he really hated SHIELD. Despite their faulty equipment, their too-easy-to-hack systems, their mostly incompetent agents (save a fiery redhead and a real-life Katniss Everdeen), despite all of that, Tony really hated them specifically for their utter lack of security and poor architectural skills. As the first one into the super-secret SHIELD tunnel, he got a pretty good look at the numerous charges set sparingly on the walls. He had just turned his head to shout out in warning when the first one blew up in his face. He didn't quite remember what happened after that until he woke up to Friday's voice.

"Sir?"

"Unnngh," he grunted in response.

Tony felt like he had been thrown into a high-powered dryer. His head was pounding, his chest uncomfortably tight.

"Sir? Are you conscious?"

"Regrettably," he said gruffly. "What happened?"

"It would appear that the tunnel has been compromised."

Slowly, Tony opened his eyes, squinting a bit at the light of the helmet display in front of him. Several levels were approaching the red zone, warning messages flashing across the holographic screen. One, of which, was the oxygen level.

"Friday?"

"You are currently buried under several tons of rock. It would appear the oxygen reservoir is running low."

"How long have I been out?" he asked.

"About two minutes, sir."

"The others?" he asked, dread curling in his stomach.

"I don't know, sir. There are several dozen dead, but I cannot tell which ones."

"What about communications?" Tony asked.

"Yours is functional. I do not know about the rest of the team's."

"Patch me through. Right into the car radios if you have to."

A couple moments passed as Friday reset the communications. Tony wanted to shift as something hard was pressed into his back, but he couldn't move at all, and through the screen in front of his face, he could see only darkness. Tony had the sneaking suspicion that he was, in fact, completely buried.

"Functional, sir," Friday said.

"Guys? Anyone there? Hey!" Tony shouted.

The engineer had long since forgiven the newest member and local telekinetic/telepath, but he still saw all of his partners piled up, dead, when it was sometimes a little too quiet at the tower. He didn't think he'd be able to stand it if that vision were to come true only under slightly different conditions. After what seemed like a millennium, a gruff voice called back, "Barton and Pietro here," and a picture of each showed up on Tony's screen.

"You took your time," Tony said, but beneath the snark, he was actually flooding with relief.

"Oh shut up. I was only a minute," Clint said, but then,"Where are you? You hurt?"

Tony wasn't exactly sure how to answer that as he still couldn't feel his legs, but Friday pulled up a diagnosis.

"Friday says I'm fine, but I'm going to run out of air in, oh-," he started, glancing at the screen again. "-about twelve minutes. Nothing major."

"Of course. No big deal," Pietro said.

Tony laughed despite himself.

"And how are you guys doing? Feeling a bit snug?"

"We actually made it out thanks to Speed here," Clint said to which Pietro chuckled.

And then a thunderous roar came over the line. Tony swore he could hear it outside of the line too, through the rock.

"Oh, and Bruce is here too," Clint added.

"Is he alright?"

Another roar.

"Just turning a bit green."

Clint:

When the first bomb went off, Clint did not even have enough time to jump in surprise. He heard the boom and then he was just...not there anymore. He wasn't sitting in the car, trapped in the tunnel, he was kneeling outside of it, sun shining down on him. By the time he was over the shock, Bruce was there too. And Pietro.

"Oh my god," he said as the sound of cars squealing and charges tearing the tunnel apart washed over him.

And like a sheet being spread out over a mattress, the tunnel collapsed just as Pietro made to run back in.

"No!" Barton shouted and was surprised that he got ahold of the Enhanced in time.

"My sister!" Pietro shouted in reply, tugging his arm from Clint's.

Pietro turned to the tunnel in earnest, but he was too late and the sound of the mountain slowly began to dim as the entrance crumpled.

"Jesus," Clint said under his breath, taking his head in his hands. "Oh no. Oh no, no, no."

"Wanda," Pietro mumbled and became a blur as he worked at the rubble, pulling rocks and earthy debris to the side. "Wanda. Wanda!"

Clint could still hear the bombs going off deep in the mountain, the only hint at something dark and sinister in the otherwise serene landscape. He had never felt so helpless in his life, so small. He wanted to dig into the rock as well, but it was so futile. Despite the deep ache the thought of it brought, Clint imagined where Nat was. As best as he could remember, she was with Steve in a car a couple vehicles ahead of him. Perhaps they could dig them out? He dismissed the thought immediately and decided he would not get his hopes up for anything of the sort. She's dead, he thought. There was no getting out of that, no surviving that. Clint was pulled from his dark thoughts as a strangled shout issued from Bruce. He turned to look at the scientist who was kneeling on the ground, fists clenched tight.

"Pietro," Clint said, trying for the Enhanced's attention. "Pietro, we need to calm him down."

He turned from his work and glanced at Bruce who was steadily turning green. Pietro's eyes widened in fear and he said, "What's wrong with him? Why is he turning?"

"He's in shock," Clint said and knelt before the shaking man. "Bruce, can you hear me? Bruce."

Bruce shoved him away and rolled on his side, trembling violently and letting loose another gruff exclaim.

"Get away," he growled.

He jerked, scrambling to hold on, but he was already shifting into his larger form.

"He's going to turn," Clint mumbled, backing away. "And it's not going to be pretty."

Just then a smug, pompous voice came over the radio and Clint would never have thought he'd be so damn happy to hear it.

"Guys? Anyone there? Hey!"

Clint looked at Pietro and couldn't help the grin that fell on his face. Tony was okay. Tony was alright. He would know what to do, he was smart. Tony would help them.

"Barton and Pietro here."

A moment later came a gruff reply, "You took your time." And Clint stifled a laugh.

"Oh shut up, I was only a minute." Clint said. "Where are you? You hurt?"

Tony's voice came back over the line, a little more dramatic than strictly necessary.

"Friday says I'm fine, but I'm going to run out of air in, oh, about twelve minutes. Nothing major."

"Of course. No big deal," Pietro said.

Tony's laugh came over the line. "And how are you guys doing? Feeling a bit snug?"

"We actually made it out thanks to Speed here."

Bruce then gave an almighty roar.

"Oh, and Bruce is here too."

The line fell silent for a moment and then, "Is he alright?" Bruce roared again.

"Just turning a bit green," Clint said.

He didn't wait to hear the response. The archer backed away from the growing man, once again in awe over the Hulk's immense size and bulging muscles.

"Pietro," he said, reaching back for the newest Avenger. "Stand back."

Banner's body seemed to explode with energy, his chest, arms, and legs swelling in size, all the while turning green. He turned over again, resting on his forearms and shins, head bowed and finally still. It was almost like the calm before the storm.

"Bruce?" Clint said after a moment when the tremors had all disappeared from the huge green form. "Bruce, are you alright?"

Like another bomb going off, the Hulk roared and slammed fists the size of car engines into the ground. Pietro grabbed Clint again, and pulled him out of the way as the Hulk turned his angry confusion on the archer. Clint jumped back and suddenly found himself between an angry green giant and a mountain.

Wanda:

Her first instinct was to grab for her brother, to hold his hand in hers and make sure he was alright. In the week after Sokovia, she was by his bedside day and night, clutching that hand and tending to her brother's wounds as best she could. Dr. Cho's handiwork did the rest and now her big brother was up and Avenging again. He had been with Clint a few cars behind her when it all started, and she fought the instinct to grab for him. He was out of reach, and she had bigger problems to deal with. The first few rocks came crashing down, the earth swallowing them up. She threw her hands above her head, fingers contorted as she weaved a red net, a shield. She heard Thor shout something, he in the seat beside hers, but the sound of the bombs was too loud to distinguish it. Like a tank, the first enormous chunk of earth fell. She shouted, surprised by just how hard it was to keep the rock from crushing the SUV. Immediately, she began to shake, and she knew it wouldn't be long for the weight to become too much. She had to hold on or they all would die.

"Hold on!" Maria shouted from the front, clutching the steering wheel as the car came to screeching stop.

The vehicle lurched forward, wisps of scarlet curling around outside and holding up the rock. Thor reached for Mjӧlnir and ripped away his seat belt. He tried as best he could to take a fighting stance, but there was nowhere to go, and no enemy to swing his hammer at. In all honesty, Wanda thought he looked pretty out of his depth, but she was soon distracted by more rubble.

"Lady Hill, what has happened?" he said, leaning forward to speak with the agent.

"What does it look like? Someone's bombed the tunnel!" she said as the charges continued going off in the deep. "Look out!" she shrieked as a large boulder fell through Wanda's defense.

It clipped the front passenger side, making the car jerk and the engine go dead. Maria threw her hands up to shield her face as the front window was busted out and glass went flying. Wanda yelped as she felt the rock settle above them and become solely bolstered by her.

"Thor, I need-," she said through her teeth, breathing hard and trying not to pass out.

It was all she could do to keep the rock from falling on their heads, taking every ounce of concentration and mental strength. Even so, she was slipping. She could feel her mind giving out, and with a whine, the roof of the SUV began to buckle. She put her palms out flat on the roof, pushing against it physically and mentally. Thor then threw his hands up as well, and Wanda felt sweet relief. She still pushed against the rock, but it was now a team effort.

"Fury, come in," Maria said from the front, finger on the radio in her ear. "Clint? Tony? Anyone there?"

Maria slammed her hands on the dashboard in frustration.

"Thor, are you alright?" Wanda said through a clenched jaw.

She looked to the thunder god whose huge arms shook just slightly under the weight of the rock.

"I am fine, Lady Maximoff. This is manageable," he said. "Just don't let go," he added, repositioning so that he was pressing his shoulders against the top of the roof and lifting with his legs as well.

"Wouldn't dream of it," she said. "I doubt you would last as long I as I did."

"Is that a challenge?" Thor said with a strained chuckle. "Because I think I could."

Maria turned from the front seat and said in a slightly crazed voice, "I swear to all that is holy, if you let go and crush us all because you're both too busy with a pissing contest, I will come back there and kill you two myself."

Thor gave another chuckle, but then the weight above them shifted again. Wanda shouted unintelligibly, focusing all of her strength on the rock and earth above them. Maria froze for a moment as the two Avengers in the backseat slowly regained control. Then she was at the radio again, calling out for help as the roof of the car sank little by little.

AN: Hope you liked it! It is obviously a little AU as Pietro is alive (curse you, Joss) and Bruce and Thor are still with the team.

AN: 6/21/15-updated for the misspelling of Sokovia. Whoops