IX. Ghost Riders
The Doctor stepped over the burnt out hulk of a sentry and into the corridor. No further guards were immediately visible.
The design of the structure had more in common with a resort than a military base. The walls glowed softly and gentle light shone through swirls of pulsing colour. The ambient light was a pleasant amber, typical of Varian sensibility. The other feature typical of Varian architecture was the size of the corridor: the ceiling barely cleared the Doctor's head, and he crouched to keep clear of it. It allowed precious little room to manuever.
His sonic out, he scanned for the TARDIS's location.
"Any luck?" River called to him. She had detached the gun from one sentry, and was working on a second. The Doctor didn't like guns. Except when River was wielding them.
Before he could answer, they both jumped as a series of pounding, staccatto thuds echoed down the corridor. The reinforced doors that sectioned off segments of bulkhead slammed into place, effectively cutting them off. His ears ringing, the Doctor said, "I found the TARDIS, but..."
A new sound reverberated through the corridor: turbines powering up to full speed. River cursed a blue streak in Altaran. "Fred's playing with the ventilation system. I wonder what he's pumping in?" River moved quickly, stripping the sentries of their energy packs.
As the Doctor scanned, River pushed him against the corridor wall, and stood in the centre of the hall, holding two disruptors, one trained on either door, ready for the onslaught to begin. An image of Leela, the fierce huntress, appeared in his mind's eye. "I don't like this," River said,. "We're stuck on the wrong side of a shooting gallery. Talk to me, Doctor - why are the fans on?"
He took a deep breath, held it in, analysed it. "I don't know. I don't think it's poison." Another breath. Something... "It's the oxygen. Fred is pulling out the oxygen." He turned on the spot and scanned again. "I found the TARDIS, but... Too far." The Doctor indicated the corridor that was now behind him. "Two corridors down, one level up and," he squinted at the sonic, "a load of energy readings in between. We need somewhere else to go."
The fans continued their steady hum. "Which way, Doctor?"
"Scanning, scanning… Aha! There's an untapped oxygen reservoir that way." He pointed to the door they were now facing.
"How far?" River was already running to the door, levelling her gun.
"Two corridor segments, then a right. It's a big open space. Lots of oxygen." He fell into pace behind her, glancing worriedly over his shoulder, to the opposite - and still closed - door.
The light from River's disruptor flashed, and he heard the telltale pop of damaged bulkhead. An access plate clattered to the floor, revealing a control panel. The Doctor slid to a stop in front of the panel and reached inside. "Magnetic lock, going to assume Fred's deadlocked everything," he muttered as his fingers felt along the controls and exposed wires. The surface was hot from the blaster, but at least the suit gloves offered some protection. "Almost... old fashioned hotwiring job... almost... got it!"
The locking mechanism powered down with a whine. "Oh, bother," the Doctor said as his fingers found molten metal in place of the power door control.
"What?" River asked as she turned her head from side to side, watching for movement from every directly. "Is it locked?"
"No, the motor is out, I have to open it..." The Doctor threw himself to the ground in front of the door, his fingers desperately seeking a hold. Mercifully, the door released a centimetre when the magnetic lock blew. "Got it!"
But he didn't really have it. The thing was impossibly heavy. His fingertips slipped once, twice, and finally he got just enough hold to pull up. He grunted with effort, but it did not budge. He sucked in several breaths - noting the steady drop in oxygen level - and kicked in his adrenal glands, focusing his mind and body into opening the door. Like an Olympic power lifter, he howled with the effort. Slowly, he raised it to his knees, and then his waist.
"River, go, that's all I've got," he panted.
She was already kneeling, sweeping her gun over the next corridor, checking for guards. "It's clear - for now." She slid into the next compartment. He worked his way through, first sliding under in on his hands and knees, and then, while she helped stabilise it, finally rolled away. The door slammed shut behind them, narrowly missing his ankle.
"This is taking too long," River said, breathing heavily, "and look, another door."
"Take it at an angle," he said, even as she fired again. This time, though, she didn't melt the whole unit and they were through in a matter of seconds.
They ran toward the third door, River leading, finger on the trigger. Before she could fire, they heard the lock disengage on its own. The Doctor imagined Fred clearing the way for the guard robots to advance - if Fred was going to utilise the guards, the doors had to open to allow their movement. River must have had the same thought, because she shoved him against the bulkhead, leaving the centre of the hall free for her to move.
The blast door sprung open and River's disruptor spat fire. The corridor was full of competing energy beams, but River made quick work of the squad. "Let's go," she said hoarsely.
"Last one," the Doctor said, his own voice only marginally stronger. They had only a minute, maybe two, before incapacitation. River banked a blast at the last control panel as she ran, and it blew open in a shower of sparks. The Doctor flung up an arm to shield his face.
"Arrgh! A little more caution, please!" He was already reaching inside the panel, separating wires.
"No time," she snapped.
He would have told her she was right, but it would have been an unnecessary waste of oxygen. The release sounded and the door slid open, but was stuck half-way. They scuttled through, and it slammed shut behind them with a boom.
"Oxygen?" River looked at him expectantly. Her breathing was laboured, her chest rapidly rising and falling.
"Close." They were now in a T-shaped intersection, and a right turn down the stem of the 'T' revealed another blast door. This one had a window and was marked in Varian writing the Doctor only barely noted: 'Crew Quarters.'
Before they could contemplate this obstacle, a familiar hissing and the deep thud of a magnetic lock release filled the corridor.
River raised the gun to her shoulder, but dropped it again when she realised there was no exterior access panel. She glanced at him for just a moment, desperation and fear in her eyes. He nodded.
The hum of the hovering sentries approached. River jogged back to the junction to give him more space to work. Desperately, he ran his fingers along the edges of the door. No mechanism. Must have been voice or DNA activated.
A fierce volley of blaster fire exploded behind him. Hold them off, River. Be careful.
His next breath came in a gasp.
River, I'm sorry.
With nothing left to try, he scanned with his sonic.
The blaster fire stopped, and River ran back towards him, her hair singed and her face pale. She had lost one gun, and was waving the remaining weapon wildly at him.
He checked his reading, squinting through the stars filling his vision. That was odd. He switched the setting and sonicked the door.
It slid open.
He didn't have time to admire his luck - if that's what it was - because River pushed him inside. He tripped and fell to his knees, and River followed him in, but stopped and turned, facing another trio of sentries speeding towards them.
Three shots, and two had fallen to the floor, sparking and twitching. The third was still flying toward them, even though its gun was hanging precariously from its arm. River ducked out of the way as it zoomed past, and the Doctor used his sonic to shut the door.
The last sentry slammed against a stanchion behind them, and River delivered the coup de grace.
Meanwhile, the Doctor sonicked the door into a clever - if he did say so himself - lockdown. It wouldn't hold against sustained disruptor fire, but at least Fred wouldn't be able to immediately open it.
It was all about buying time, and oxygen. His lungs rejoiced at the richness of the air, and he remained on his knees, sucking in deep breaths.
River swam into his field of vision, and he caught the disruptor she tossed him. She, too, was breathing heavily, and the colour had returned to her lovely face. "That's better," she nodded at him.
"Isn't it?" He checked the rifle's power pack. Not bad, but not near enough.
"But it doesn't make any sense," River replaced the power pack in her rifle.
"Check with me later," the Doctor raised the rifle to his shoulder, sighting down the barrel, ready for the next onslaught.
River was doing the same. "If we have a later."
The door would be blasted away any second. In the his hands, with the butt against his shoulder, the gun felt both uncomfortable and reassuring. The Doctor didn't take the time to analyse it overmuch. Beside him, River waited. not as tense, perhaps, as her instinctive - he refused to think programmed - warrior's reflexes took hold.
Why was the door still there? It had been over a minute. Hearts sinking, he turned to consider other entry points.
They were in what could only be described as a lounge. Upended tables and chairs littered the large open space, and the wall was in fact a huge, sloping window. The best view in the entire base: looking out over the crevasse, and above them the beautiful and violent storms battered the surface of the moon.
That wasn't the only thing outside.
His arm went slack. The rifle slid from his shoulder and drooped to the floor. Sentry robots assembled in formation, hovering on the other side of the glass.
He stopped counting at seventy five.
"Doctor? They're just.. waiting. They could have us easily." River stood from her crouch, and he read the wonder in her face as she stared at the armada outside.
He took a few tentative steps to the door and peered through the narrow window. Another eight sentries hovered, mechanically patient. In a holding pattern.
"Okay then, it's later. Explain."
The Doctor gave a nervous laugh - born from relief and the sudden, vivid memory of her mother saying the same thing to him many, many times.
"Doctor!" Now River's hand was on her hip and the gun perched on her shoulder.
"Ahem, yes. I think... yes, that must be it. Our friend Fred is essentially the chief of security of this base, but he was never meant to be the sole proprietor."
"The crew."
"Exactly. As clever as they were with their artificial intelligence and automation, the Varians were keenly aware of the limitations."
"Yes, you're right. Failsafes."
"A hard-coded failsafe: the security system cannot go all guns-ablazing into the crew quarters. At least, not without a manual override."
"An override that can never come," River whispered.
"Good thing, too. I mean seriously, who builds a security system that can indiscriminately kill friendlies?"
River looked out across the canyon floor, her hand splayed on the glass. The silent guards floated by, like ghosts. "There's only one problem, It's just another prison."