They rendezvoused with Corporal Barker and a squad of the station's marines a level above the maintenance areas. Even here the security was light, a level largely dedicated to equipment storage formed of a honeycomb of narrow, block-like passages. Scattered all over the level were floor hatches leading down into the maintenance decks, filled with power conduits, climate control nodes, lighting circuitry and spare parts.

Barker approached them, flanked by six fully armed and armoured colonial marines. The others had their standard issue R-11 assault rifles, but Barker himself carried a hefty rectangular-barrelled shotgun.

"Flint," he said, inclining his head. "Seems like you brought us a pack of trouble."

"Don't remind me," Darien replied with a grimace.

"We're spread pretty thin – right now I'm all you get to cover maintenance."

"Try and keep the exits covered." He motioned towards the assembled Blink squads with a flick of his head. "We'll go in after him."

"You don't know he's down there," Barker pointed out.

Darien gave the burly marine a dubious look. "Well, where would you go if you were trying to hide from the entire station?"

Barker frowned but didn't argue the point.

He turned to his fellow operatives. Taggs' people looked less skittish than they might have: having already had one run in with Tannis Brock, Vandal's members knew what they were in for. Panther Squad were not so prepared. Their leader, a tall, dark-skinned individual named Bandle, looked impassive, but the five operatives behind him seemed like they hadn't quite wrapped their heads around what was going on.

"Okay, pull up your mappers," he told them. "We've got a lot of ground to cover. Panther, make your entry at access hatch G-13. Vandal, enter at R-4. We'll go in at A-9. That gives us a triangle. Use your local motion detectors; sweep every section as quickly as you can, running station-clockwise. Barker and the marines will keep a rolling patrol above the access hatches." He glanced back at them; Barker nodded his agreement. "I've said it before but I'll say it again: if you find our target do not engage alone. Mark him, stay with him and call for back up. He is incredibly dangerous."

The operatives gave him a low murmur of understanding.

"Alright then. Move out, and stay safe."

*

The maintenance decks were cold, cluttered and claustrophobic. More importantly, they were a tactician's nightmare. Even moving as fast as they dared – even with the portable motion trackers – Darien knew they were taking too long, having to stop and cover every corner, every shadow; every nook and cranny that might be hiding their quarry. It would have been child's play to set up an ambush on an unsuspecting unit. He could only hope that the other squads were taking similar precautions.

He moved up to a junction in the narrow maintenance passage, hugging his carbine close to his chest. Idas joined him, jackhammer primed and ready. He met the other operative's gaze, nodded once, then turned and aimed in one fluid motion.

"Clear," he said quietly. Idas then slipped past him to cover the next corner. Then one by one the others filtered through after them, moving silently, their movements honed by years of experience.

At least until Uther's foot connected with a discarded empty canister. It toppled with a clang that in the confines of the maintenance level reverberated deafeningly. The young man's face screwed up as though in physical pain, waiting for the echo to die. For a moment they all stood rigid, letting the silence return.

"Ever hear of 'stealth'?" Hekket whispered. He saw Amber clamp a hand over her mouth, stifling a laugh as Uther glared at the medic.

"Belt. Up," he hissed.

"Alright, alright," Darien said, heading off any further exchange. "Keep moving, children, and watch your footing." They set off again, and as Niamh prowled past him he caught the glint of her white teeth as she grinned, shaking her head in amusement.

Minutes passed as they continued their methodical journey through the underdecks. They checked in twice with Smith and the other Blink units scattered around the station, but so far Brock had yet to reveal himself. Darien's mind raced as he tried to place himself in the assassin's shoes. Where would he go? What would he do? Already he'd played one hunch by coming straight to the lower levels, but that would only delay detection. Tannis Brock was not going to run around playing cat and mouse without some kind of plan.

The shuttles: that had to be the endgame. Brock wanted off this station and he'd already proven himself a more than capable pilot. How he planned to get there through an army of marines and Blink operatives was anyone's guess right now.

His train of thought was arrested when he stepped around the next ninety-degree corner, aiming his carbine down the metal passage. At the far end he saw a shape on the ground, a human shape. Instantly he held up a fist, bringing the others to a halt.

"Hekket, Amber – you getting any motion hits?"

"Nothing within two-hundred meters," Amber replied. "If he's nearby he's not moving."

Darien's jaw tightened, a sick feeling settling in the base of his stomach as they started moving again, making their way towards the shape. Before long it became coldly apparent what they were looking at. A dozen yards ahead of them lay the crumpled form of one of the station technicians.

Before anyone could stop him Hekket scuttled forward and dropped to his knees by the man's side, pressing two fingers to the side of his neck. When the others approached he looked up grimly.

"He's dead." Hekket stood, shaking his head. "Ivoh Akkers – technician 2nd class – his neck's been broken." He glanced at Darien. "Looks like you were right."

Darien nodded unhappily. He could almost feel the surge of apprehension that rolled off the other members of the squad and he didn't blame them. Beside him he saw Niamh's face twist up in frustration, her hands snapping tight around her carbine and he knew what she was thinking. The longer Brock was loose, the more people were going to die.

"Hammerhead Squad to all units," he said, keeping his voice measured. "We've just found the body of technician Akkers on the maintenance levels, killed in action. I can confirm target's presence in the lower levels. Blink Squads Tundra and Rigel, make your way to level three and meet up with Corporal Barker's squad. We need more manpower to cover the exits. Smith, if you can spare an extra marine unit I'd appreciate it."

"Copy that, Hammerhead Squad," Smith replied. "Redirecting now."

He exhaled a long, slow breath and nodded to the others. "Let's keep moving."

To their credit, his companions didn't flinch despite the body they'd just discovered. They fell back into their training as though nothing had happened, focusing on the details of their formation and their movements to keep their minds clear.

Darien, however, was still thinking about just what Brock's endgame would be.

"If you were trying to get to a shuttle," he whispered to Niamh as they moved. "How would you get there undetected?"

"He's already done strike one," she replied, scanning the next passage with the barrel of her carbine. "Without the internal nets this station's got a lot of hiding places. Then if it were me, I'd steer clear of the main hanger."

"And go where?"

"One of the emergency evacuation launch bays."

He considered that for a moment. "There's one on deck five, isn't there?"

"I think so." She glanced at him. "You think that's where he's headed?"

"It's where I'd go. He has to know the main hanger's heavily guarded. Without a way to track him one of those auxiliary bays will make a softer target."

Niamh nodded. "Makes sense."

"Barker," he said sharply into the comm. "I think Brock's going to make a break for the auxiliary docking bay on deck five. Get some of your people to cover the nearest access hatch. Rigel Squad – Vanna, you read me?"

"Loud an' clear," Rigel's squad leader replied, her voice thick with the drawl of her home planet's local dialect.

"Redirect to the deck five bay and dig in. If Brock comes your way do not let him near those shuttles."

"Copy that, Hammerhead. We are en route. Rigel out."

He hoped it wouldn't come to that, but Vanna and Rigel Squad were a good unit with some experienced operatives. Now he needed to trust in the other teams to do their jobs. His job was to hunt down Brock in the first place.

It turned out to be far from a simple task. After another fifteen minutes of creeping through the maintenance passages neither they, nor the other Blink teams down with them came across any more signs of Brock's presence. They were running out of passages to search, slowly tightening their net around the access hatches closest to the elevators leading to the auxiliary bay.

"Guy sure lives up to his rep," Idas muttered angrily as they emerged into yet another corridor. "Feel like we're chasing a freakin' shadow."

Darien had to agree. He tapped his earpiece. "Barker, anything topside?"

"Not so much as a whisper," the marine replied and he seemed just as confused. "Where the hell is this guy?"

"And Rigel, all quiet at the bay?"

"Affirmative."

"Then what..."

"Darien, wait!" Amber's sudden yelp was shrill urgency and he whirled to look at her.

"What?"

"That technician we found – Akkers," she blurted out. "Did he...did he have an earpiece?"

Beside her Hekket's eyes went wide. "I didn't look."

Darien felt like someone had just hauled all the air out of his lungs. None of them had checked. Why hadn't they checked? If Brock had an earpiece and was tuned into their comm frequency without them knowing...

"Crap." He gritted his teeth in frustration. No wonder Brock hadn't revealed himself. He knew where the Blink teams and marines were moving. He was one step ahead.

"Space," Uther rumbled. "How are we supposed to co-ordinate to catch him if he's listening to everything we do?"

Darien shook his head, already thinking of their next move. They needed to make Smith and the rest of the station aware, but then they needed to get ahead of Brock. Delving into his memory, he knew that the next nearest auxiliary bay was three decks higher on the opposite side of the station. Brock was likely already on his way to it, but if he warned the other teams, their quarry would simply pick another target. Hammerhead Squad needed to act, and now.

"All teams," Darien barked into his comm. "We have reason to believe Tannis Brock has secured a radio and is listening in on our transmissions. Until further notice stay off comms! Stick to your assigned stations. Panther and Vandal Squads, rendezvous with us at Hatch B-12 immediately."

He didn't wait for the others to question his decision making. He simply set off, clattering through the passages towards his chosen meeting point, and the patter of running feet behind told him that his team mates were in hot pursuit. Skidding around corners and hurdling stray equipment he hurtled through the maintenance deck as fast as he could, aware that every second they wasted Brock would be getting closer to his target.

They found both Panther and Vandal Squads waiting for them at the assigned hatch, all of them looking perplexed and worried in equal measure. He saw Taggs open his mouth to speak and held up a hand to keep the inevitable questions at bay.

"We don't have time," he snapped. "Just listen to me. Taggs, take your people topside. Find Tundra Squad, Corporal Barker and as many marines as you can. Then bring everyone to the emergency evac bay on deck eight. Bandle, head for the bay on deck five and rendezvous with Rigel Squad. If Brock switches his target again you need to be ready." He glanced back at Hammerhead Squad. "We're going straight to the bay on deck eight. Everyone get ready to Blink – aim for the nearest main passage. We don't have time to hoof it up there."

They looked at each other and then Niamh spoke up, "then what are we waiting for?"

He smiled thinly at her, then closed his eyes. "Five meter spacing. Blink on my mark. Three...two...one..."

The absence surged over him for a fraction of a second, the distances and specifications of the Blink station's constructions filling his mind as he moved his body from deck to deck. Then he materialised in an empty passage, unfolding his body and aiming his carbine left and right. Seconds later Amber appeared, closely followed by Niamh. Hekket came next, then a few seconds after him Uther and Idas Blinked into existence.

"Everybody on me," Darien called and the others quickly fell into step with him as he set off at a jog towards the emergency bay. Only big enough for a handful of shuttles, the auxiliary bays were seldom used – certainly never while he'd been an operative – and he hoped Smith and the marines had thought to post guards at each of them.

The upper deck corridors opened out before them, far more spacious than their counterparts on the maintenance decks. That meant a lot fewer places for Tannis Brock to hide on the way to his escape route and a much faster sweep for Hammerhead Squad. He wanted desperately to radio and check on the progress of the reinforcements he hoped were on their way, but he couldn't take the chance. He had to simply hope that his guess was right; that they could take Brock by surprise by predicting his move.

It turned out his hunch had been well-placed. One turn away from the auxiliary bay Darien heard the crack of an R-11 rifle and his heart jolted. He glanced once at Niamh alongside him and they both broke into a run in the direction of the gunfire.

His fears became an abrupt reality when the operatives clattered around the corner to find the bodies of two marines lying in a heap on the floor. At the far end of the passage the large circular door of the outer airlock stood, closed for the moment.

Even from this distance Darien could tell the marines were dead. Every inch of him wanted to go hurtling forward but he checked the impulse, forcing himself to slow down and approach with the training embedded in his mind. He moved quickly and quietly, carbine aimed, checking for any sign of Brock. The others fanned out behind him, taking up positions as he came to a halt.

"Cover me," he hissed.

Dropping to one knee he bit back a curse. The female marine had a ragged slash across her throat and blood was still pooling on the floor beneath her. Her companion's head had been twisted around at an unnatural angle. And his weapon was missing.

"CONTACT!" he heard Idas roar.

His head snapped up sharply and he saw Brock standing in front of the airlock holding the dead marine's rifle. Behind the assassin the airlock's system panel lit up, whirring into readiness.

A torrent of bullets from the commandeered R-11 poured down the passage, scattering the operatives like startled birds. Darien threw himself to the deck in a heartbeat, rolling out of the line of fire, but he heard a scream from behind him. Turning over to look he saw Amber on the ground clutching her left side, teeth gritted in agony. He could see the pockmarked impacts on her chest plate where a spray of fire had clipped her. Glancing back down the corridor he saw the outer airlock iris open and Brock darted inside.

Scrambling upright he turned back to his injured squadmate. She slumped in a sitting position against the wall and Hekket was already by her side, checking the injuries. After several heart-stopping seconds boomed by in Darien's head the medic looked up at him.

"She'll be okay," he said quickly. "The armour took the brunt of the hit but I need to get her to the infirmary." He jerked his head in the direction Brock had taken. "Go catch that murdering bastard!"

Darien felt anger rise within him and he spun around, bolting down the hallway with Niamh, Uther and Idas hot on his heels. He jerked to a halt at the airlock and peeked around into the next passage, carbine raised. A bullet cracked off the frame beside him but he ignored it, instead squeezing off a shot from his carbine and catching Brock in the shoulder. The heavy set man's face twisted up in a grimace of pain but he kept firing and Darien had to jerk back out of sight. More bullets smacked against the frame, but then he heard a curse as the rifle's clip ran out. Moving so quickly Brock hadn't had time to fleece the marines for extra ammunition.

When he leaned out again, however, there was no sign of the assassin. The passage ahead of them was short and heavily reinforced with heavy ribs of thick metal, leading to a smaller door – the final barrier to where the emergency evacuation shuttles waited.

"Where the hell did he go?" Niamh hissed.

Darien shook his head. The rifle and empty shell casings lay discarded on the floor but of their quarry there was no sign.

"Brock!" Darien barked. "Give it up, you've got nowhere to go!" As he spoke he crept forward, motioning the others to flank out to either side of him. Keeping his carbine aimed at the last place he'd seen Brock, he started to circle in a slow arc to see what was behind the supporting rib of the passage.

Before he could get a good look a spherical object rolled out into his path and exploded.

The flash left him dazzled for only a few seconds but before his vision could clear fully a heavy fist crashed into his face and sent him sprawling. Pain exploded in his skull but he shook it away, retaining enough of his senses to roll with the impact and come to his knees. When he looked blearily up he saw Brock's towering frame flying towards him through the smoke of the stun-grenade.

With the instant he had to react, Darien threw up his arms and the assassin's booted foot hit the reinforced vambraces instead of his face. It still knocked him flat, but then three other bodies hurtled into the melee. The deep thump of Idas's jackhammer sounded, then a knife appeared in Brock's hand. He slashed wildly at the burly operative and Idas fell back with a howl of pain, clutching his face.

Darien scrambled upright as Brock turned to run, but before he could get to the airlock, Uther's lanky frame appeared to bar his path. They twisted and manoeuvred around each other for a few seconds; Uther clouted him across the face and Brock replied with a knee to the gut that lifted the operative off his feet. Unable to take a clear swing, the assassin twisted awkwardly and belted Uther across the head with the pommel of the knife, sending him spinning into the wall of the passage.

Dragging his pistol free, Darien took aim, squeezing the trigger just as Brock lunged at him. The wild shot clipped his adversary's hand, causing the knife to fall from his grip, but didn't slow him down. They clashed and instantly Darien knew he was in trouble. While amongst the other operatives he was a good hand-to-hand fighter, Tannis Brock was a grown man and a professional killer.

Desperately he wrenched his body backwards, trying to angle his pistol to hit a more vital part of Brock's anatomy. He kicked hard at the man's knee cap; connected hard, extracting a grunt of pain. Then Brock took a hold of his arm and flipped him head over heels, slamming him hard into the deck and driving the wind from him and he lost his grip on his side-arm. He gasped in pain, rolling onto his front.

When he looked back he saw Niamh leaping into action. She had her own knife out now and she circled viciously, trying to block the route to the shuttles. Brock lunged toward her and she pivoted away, lashing out at his face with her blade. He dodged, swerved and trapped her knife hand under his arm. Then he fastened his free hand around her throat, and Darien could only watch helplessly as he lifted her bodily and smashed her down into the deck. She let out a shriek and her knife went clattering across the floor. Brock reached down and pulled her pistol from its holster before standing up.

Darien felt a cold chill of fear as he stood staring down the barrel of the gun. His jaw tightened. So this was how everything ended, shot dead on a station that until two hours ago had been the safest place in the galaxy. Fury gripped him like a hand of fire.

Brock's face morphed into an evil smile. "Looks like I win this round, kid." His finger tightened on the trigger and Darien braced himself for the end.

Before that shot could be fired the corridor was filled with the clamour of gunfire and lance impacts clattered against the metal of the walls. Brock leapt back into cover with a curse, turning his attention to the newcomers.

Darien dropped to the ground, rolled aside and looked back down the corridor to see Taggs running at the head of two Blink teams and a squad of marines. The cavalry had arrived. Brock snapped off several shots from his pistol and then made a mad, scrambling dash the final few meters to the outer airlock. Bullets and lances streamed back and forth, but in one frantic flurry Brock punched in an access code and the door slid open. Before it had finished opening fully he dived inside.

Leaping back to his feet, Darien swept up his fallen pistol and sprinted for the airlock as it started to close again. Adrenaline pumped through his veins as he started shooting wildly, at the closing mechanism. The clang of bullet impacts stung his ears, but it was too late. A wordless scream of anger ripped free from his throat as the door boomed shut just as he reached it. He slammed a clenched fist against the metal so hard that lightning bolts of pain shot up his arm. Teeth gritted, he let his head fall forward in defeat as the sound of the shuttle boosters fired from beyond the airlock.

Brock was gone.