The spherical bulk of Blink Station Alpha, the command node of the Blink operatives' network across human space, skulked in the midst of an asteroid field, its presence masked by signal jammers, sensor scrubs and the planet's worth of building-sized rocks floating in its immediate vicinity. Concealed from prying eyes, it was a station marked on no star-chart and recorded in no galactic survey. For all intents and purposes, it didn't exist. In the unlikely event someone did manage to stumble across the hidden base, a range of much more direct defences waited for unwanted interlopers. Patrol squadrons of armed Blink shuttles flew in constant surveillance patterns, supported by formidable batteries of high-gauge rail cannons embedded on nearby asteroids and on the station exterior itself. To most of the human population of the galaxy, Blink Station Alpha was an unwelcoming place.

But as Amber approached it the little voice in her head said, 'home'.

She guided her ship toward the main hanger, through the small but constant trickle of shuttles and military corvettes that flowed in and out of the station. The navy warships slid elegantly by, shaped like long ovular blades that bristled with armaments. Amber navigated between them with the ease of an expert. While she had limited solo flight experience, her training and test scores were exceptional. Only Darien currently held a higher score on the rec-room simulator.

As her arrowhead craft floated into the gleaming white-walled bustle of the hanger she felt a tremendous sense of belonging. It was all so familiar to her – she wanted to get back into the thick of life as an operative. The automated guidance kicked in as she drew close to the docking cradle and she relaxed back into the pilot's chair. When she looked down toward the waiting bay she spotted a familiar pair of figures waiting for her and a smile spread across her face.

The shuttle descended into its cradle and she heard the muffled clanking sounds as the docking arms locked into place. She stood up, pulled the ramp release control and strode the length of the shuttle, descending the ramp with a spring in her step, kitbag bouncing against her hip. Sure enough, Darien and Idas stood waiting for her at the base of the ramp.

"Hey, stranger," she said, pulling Darien into a hug. "Good to see you."

"Likewise."

Idas gave her a nod. "Happy to be back, eh?"

"You know, I actually am." She gave him a quizzical look. "Is that weird?"

"I'd tell you yes," the hulking youth grunted. "But apparently I'm the only one around here who considers this to be work."

Darien punched him lightly on the arm. "Yeah, yeah. C'mon, Grumplestiltskin, we've got a briefing to get to." He turned back to Amber. "Go dump your kit. Smith wants us all in briefing room three as soon as possible."

Smiling mischievously, she clicked her heels and saluted. "Yessir!"

"Very funny." He pointed over his shoulder with one thumb. "Get going, missy."

Amber peeled off into a different hallway, making her way toward the main operative barracks where they kept their personal equipment stores. She let her eyes wander and strode through the familiar white-walled corridors, a warm feeling settling in her chest as she took in the familiar hustle and bustle.

Logistics staff scurried back and forth in a constant state of fervent energy as they kept the intelligence network as up to date as possible. Off-duty operatives lounged in the mess hall in their casual clothes, playing games and chatting animatedly about upcoming operations. Other young men and women in the Blink organisation trained in the gymnasiums with their adult instructors, running through hand to hand combat drills and cardiovascular circuits. Firing ranges rang with the crack of weaponry and within sealed rooms operatives-in-training would be practising the skill that made them unique among the billions of humans in the galaxy: Blink travel itself.

She remembered the first time she took that step; did the one thing that made the Blink operatives who they were. The rooms were specially designed to prevent any travel outside their walls, creating a safe environment for the operatives to practice, but that didn't make the process any less unnerving. Still, after a few months of practice Amber had made herself a reputation for being the most accurate traveller on the station. Seeing it all again reminded her just how much she wanted to be here.

Everything just felt right. She entered the barrack room and made a beeline straight to her locker from memory. Her pride still surged within her at the sight of the nameplate: Garret. A. She punched in her ID code and the smooth, alabaster door slid up to reveal her personal equipment store. The lance carbine sat in its cradle above the perfectly arranged set of Blink issue combat armour, and all around them the extra tools of the trade hung; night-sight goggles, side-arm, combat knife, an oxygen breather, aquatic and polar bodysuits – everything they would need to handle any situation. Amber breathed deeply and placed her kit-bag into the base of the locker, pausing only to don her Blink issue jacket, its right shoulder emblazoned with the shark motif of Hammerhead Squad.

When Amber made her way back through the station to briefing room three, she found the rest of the squad already waiting. Niamh, the squad's flame-haired second in command greeted her with a playful ruffle of the hair and a manic grin, her bionic eye twinkling with its emerald green iris. Hekket stepped forward a little awkwardly, digging a hand through his short crop of sandy hair.

She understood his trepidation. He'd been the one operative to advocate her isolation and examination when they returned from their last mission together. Following their encounter with the alien entity there had been the possibility that Amber, after extended contact with it, could have carried traces back to the station. Hekket had been the dissenting voice of logic, despite it putting him at odds with the emotions of the rest of the squad. When she first found out she had been furious with him, but as time had passed she had come to terms with the fact the other operative had done the right thing.

"How are you?" he said eventually.

"All the better for being back," she said, and she stepped forward to hug him. "It's good to see you."

"I..." He hesitated, slightly taken aback before he returned her embrace. "I wasn't sure...you know, after-,"

"It's okay." Amber took a step back and met his eye. "I'm sorry I reacted the way I did. You did the right thing."

"It still felt wrong." Hekket smiled half-heartedly. "But thanks."

She nodded and looked around the room for the final member of the team. Her brow furrowed in confusion and she turned to Darien. "Where's Uther?"

Darien hunched his shoulders uncomfortably. "He's still recovering."

"Still?!" She shook her head in disbelief. "It was that bad?"

"He's on the mend. They got the debris out of him and stitched up his internal organs, but the damage to his muscles and bones – he's still got a few more months ahead until he can get around unaided."

"I didn't realise..."

"He's down in the medical centre. They've got him on physiotherapy and he can shift himself around with crutches." Darien put a hand on her shoulder. "Don't dwell on it. He's going to be fine. It'll just take a bit longer before he's fit for duty again."

Amber lowered her gaze and made a mental note to go down and see Uther as soon as the briefing was over. The boy had saved her life on Titan Aquilla all those months ago, and she felt a degree of responsibility for the horrendous injuries he'd incurred in the act of doing so.

She didn't get the chance to think about it any longer as the door to the briefing room slid open and Smith entered, as cold and calm as an icy breeze. He wore the same iron-grey suit he always did, hands clasped behind his back as he walked with the grace of a man who was entirely in control. He hadn't changed in even the most minute detail. He still sported the petite set of spectacles and precisely clipped blond hair. His meridian eyes never wavered as he appraised each operative with a brief glance up and down.

"Thank you all for coming on such short notice," he began, though his voice revealed neither gratitude or remorse. "I'm aware I've cut your leave short, but this operation demands the best Blink has to offer. Please be seated."

Amber joined the others, taking a chair at the far right of the table as Smith glided to the front of the room. He activated the view screen built into the wall of the room and the image of a planet sprang up, a terrestrial world which, at a glance, had substantial ocean cover and precious little landmass.

"I'm happy to say that while this mission is of the highest importance, its value is of a more...scientific nature," Smith began, and a thin smile crossed his calculating features. "This is Marianas. It's a tertiary planet in the Tannichar System – part of the Barrcko colonial network. Ninety percent of its surface is covered with ocean and what little landmass there is shows no evidence of habitation. However, a year ago a survey team came across this." He pressed a button and the screen zoomed down to display a side on view of the ocean. The diagram showed a small facility on the surface, and directly beneath it, thousands of feet below on the ocean floor, was something much, much bigger. Amber leaned forward, peering closely. If she was reading the screen correctly there was an enormous structure on the bottom of the sea.

"What is that?" Niamh murmured, cocking her head to one side.

"That, ladies and gentleman, is a city." His smile broadened as they exchanged incredulous looks. "We don't know how long it has been there, but the survey station has spent the last year gathering as much data as possible. From the outer architecture we can determine that it is not of human origin. This is an extra-terrestrial city."

"So how do we fit in?" Darien asked, a hint of suspicion in his voice. "It's a big find, sure, but we're a not a science team."

"Indeed." Smith nodded in agreement. "The research team have hit a small snag. While they have exhaustively examined and catalogued every facet of the city from the outside, they haven't been able to find a way in. That is where you come in. External scans have revealed dozens of pockets of air within the city's structure – in fact there appear to be whole districts that have been made watertight – but they are inaccessible at present."

"So this city is built like a giant submarine?" Hekket commented.

"Given the nature of the planet this is not unsurprising. Whoever built it made sure this city was more than capable of withstanding floods. The research team has identified four points in the station exterior that they believe to be external doors but there is no way to open them from the outside short of blasting through them. With a find of this significance I'm sure you can understand why they would like to avoid using heavy ordinance."

Amber leaned back in her seat again, frowning. "Do we know how it ended up on the bottom of the ocean? I mean, it's a city. Surely it didn't just sink."

"It could have been built there in the first place," Smith replied. "Or perhaps it is ancient enough that the region it currently inhabits was once above sea level. Until we can get inside and examine it in detail there is really no way to know."

Her frown remained but she didn't press the point, instead folding her arms and lapsing into a pensive silence. Conflicting emotions of excitement and apprehension clashed in her mind as she looked at the screen. On the one hand being the first to breach such a find would be an experience nothing short of remarkable, even by Blink standards. On the other, the last time they'd willingly gone into the unknown things had spiralled quickly out of control.

Smith continued, "The operation is simple. You, along with squads Tundra and Vandal-," he broke off as Idas let out a derisive snort. The young man cleared his throat and looked down at the table under their commander's frigid glare. "You will Blink to the nearest satellite station, where you will rendezvous with the Colonial Merchant Vessel Longstride. From there you will be taken directly to Marianas and the research base. They will give you a detailed briefing on what they have discovered so far before you are taken down by submarine as close to the city as possible.

"Each squad's precision Blink operative will take a portable Nav-Rod to your assigned sections of the city, allowing the rest of the squad to follow through. Your primary mission is one of exploration. Log everything you find down there. If possible, find a way to open the outer doors to allow the research team access to the city. They have been forthright enough to forward their initial findings to us in a data packet. It has been uploaded to your personal data-pads; I suggest you all take the time to study it before shipping out." He paused and appraised the group one by one. "This could mark a monumental moment in human history – you are the best Blink has to offer and I expect you to maintain that reputation. You will be working alongside Colonial Marines, Navy, and the assembled scientific experts on Marianas. Work with them. You have unique skills, but we are all in this together. Are there any questions?"

"When do we go?" Niamh put in.

"Rendezvous with the Longstride is scheduled at fourteen hundred hours, two days from now."

"Have Tundra and Vandal been briefed?"

"They have." He nodded. "Your briefing was delayed as we had to recall you from leave." When no more questions arose Smith gestured to the door. "In that case you may go. Except you, Darien. I need to speak with you privately."

"I'm sure you can say to them anything you're going to say to me," Darien answered quickly.

Smith shook his head and his voice took on a menacing undertone. "No."

Amber stood, but she found herself hesitating, unwilling to just walk out of the room when their squad leader clearly wanted them to remain. She looked to Niamh – the other girl shook her head.

Then Smith spoke again and his voice brooked no argument. "I am only going to say this one more time. I need to speak with Darien in private. The rest of you are dismissed."