The porthole looking out onto space was located amidships on Chaplain Iktinos's ship, where Apothecary Karendin had set up the apothecarion. Pallas, the Chapter's most senior Apothecary, and Karendin worked here tirelessly, because the Soul Drinkers needed their expertise now more than at any time in their history. Pallas had just completed an examination of Sarpedon himself, the Soul Drinkers' first and most obvious mutant.

'Commander?' came a voice from behind him.

Sarpedon snapped out of his reverie and turned to see Apothecary Pallas reading analysis off a data-slate connected to an autosurgeon. The apothecarion set up in the fighter was comprehensive but cramped, packed into what had probably once been quarters for the alien crew. The autosurgeon, servitor orderlies and monitoring consoles were crammed in alongside the bulbous organic ripples of silvery metal. Wires and equipment hung from the abnormally high ceiling.

Pallas looked up from the data-slate. 'You are getting worse,' he said.

'I know.’ replied Sarpedon. 'I felt it at House Jenas-sis. The Hell is... changing. If we do not succeed, the day is coming when I will not be able to control it any longer.’

'Nevertheless.’ continued Pallas, 'you're not the worst. Datestan from Squad Hastis has increasing abnormalities in his internal organs that will kill him, or turn him into something different. We've had to take two Marines from Squad Luko off-duty entirely - one has claws that can't hold a bolt gun and the other is growing a second

'And you?'

Pallas paused, put down the data-slate and removed one gauntlet and the forearm of his armour. Ruddy scales had grown from the skin on the back of his hand and spread up past his elbow. 'They go up to my shoulder,' said Pallas, 'and they're spreading. Marines like yourself and Tellos have the most obvious mutations, but there's hardly a Soul Drinker left who isn't changing in some way. Most of them are getting worse quicker and quicker.'

Sarpedon looked down at his spider's legs. There had been a time when, his mind clouded by the Daemon Prince Abraxes, he and his fellow Marines had thought his altered form to be a gift from the Emperor. Now he knew he was just another mutant, no different in many ways to the numberless hordes of unfortunates who were enslaved and killed in the Imperium to protect mankind's genetic stability. Sarpedon had killed enough mutants himself and, if any servant of the Imperium were to so much as look at him, they would try to kill him, too. 'How long do we have?' he asked.

Pallas shrugged. 'Months. Certainly not more than two years before the Chapter ceases to exist as a fighting force. We're already losing Marines to unchecked mutation and that number will only increase. I don't know what you're planning, commander, but it must be our last chance.’

Sarpedon knew what happened to the Soul Drinkers who could no longer function properly. Most were put down when they lost their minds, taken in chains to the plasma reactors on the Bro-kenback to receive a bolt round through the brain before being incinerated. There had been few so far, but Sarpedon had felt every one as keenly as the needless deaths of the Chapter war. 'Our last chance in more ways than one.’ agreed Sarpedon. Teturact's empire is sustained by forcing the Navy and the Guard into battles that neither side can win, because Teturact has the numbers and the capacity to raise the dead. And we're heading right into the middle of it. From the information Salk brought back from Eumenix it'll be a meat grinder wherever Teturact's armies fight. This Chapter won't die out to mutation, Pallas, it'll die in battle or it will be cured.’

*We can't carry on like this, can we?' said Pallas unexpectedly. 'We have no support. The Imperium will destroy us if it can and Chaos will see us for the enemy we are. No Chapter can survive like this.’

'Carry on with the tests, Apothecary.’ said Sarpe-don. 'Let me know of any changes.' He turned and left the apothecarion, eight talons clicking on the metallic floor as he headed back towards the bridge.

THE SHUTTLE COCKPIT was bathed in eerie blue-grey light. It shone on the brass fittings of the servitor-pilot and turned the deep red upholstery a velvet black. The viewscreen swam with swirls of white, blue and grey as the servitor applied a touch of pressure to the engines, nudging the shuttle forward. Many of the cockpit's alarm readouts were incongruous beads of red on the instrument panels - the shuttle had not originally been designed for these conditions, but Thaddeus knew it would hold together. Colonel Vinn had pulled a few of the right strings with the Guard units seconded to the Caitaran command and acquired an exceptional craft for the mission. The shuttle had been fitted with reactive armour plates that even now were flexing under the abnormal pressure and cold, and the stealth mode of the engines worked on a jet propulsion principle that enabled the shuttle to be propelled underwater.

Or, in this case, under liquid hydrogen.

'Surface?' asked Thaddeus quietly.

Three hundred metres.’ came the mechanised voice of the servitor-pilot. The armatures plugged into its shoulder sockets eased into the controls in front of it and the shuttle's steering fins were angled upwards a touch, sending the craft on a gentle upwards arc through the unnaturally cold ocean.

Thaddeus switched on the ship vox. 'Lieutenant, to the bridge.’ he said. A few seconds later the door at the rear of the cockpit slid open and Lieutenant Kindarek looked in.

'Inquisitor?'

'We'll hit the shore in about seven minutes. Are your men ready to go?'

'Standing by, sir.’

'Keep the grenade launchers slung until we get well away from the edge. There'll be dampening fields to prevent the liquid exploding but we'll still have a hell of a bang if it goes off. I don't want us losing anyone to accidents, it's dangerous enough in there.’

'Yes, sir. Hellguns only until your order.’

'Good.’ Thaddeus paused, watching the liquid swirling in front of him. "What do you think of this mission, Kindarek?'

Kindarek barely thought for a second. 'High-risk and vital, inquisitor. Our kind of operation.’

'And why do you think that?'

'Because Colonel Vinn selected us, inquisitor. He doesn't risk his recon platoon without a good reason, and good reasons always involve risk.’

'No one has ever done this, Kindarek. Some have tried, but no one's ever succeeded.’

I'd imagine no one has ever tried taking this way in, sir.’

Thaddeus smiled. You're quite right, Kindarek. I hope.'

Two hundred metres.’ said the servitor.

'Prepare your men, lieutenant. I want men on point as soon as we hit the shore.’

Kindarek saluted briskly and headed back towards the crew compartment. Since Thaddeus wasn't an officer the gesture was inappropriate, but Thaddeus didn't point it out. It was probably force of habit. Kindarek seemed a soldier who learned his habits early and never strayed from them - it had made him a soldier trusted by Vinn to lead his recon platoon, as professional and unshakeable a body of men as the Ordo Hereticus could make out of mundane troops.

Shapes loomed past, half-glimpsed through the near-opaque liquid, picked out briefly by the floodlights mounted under the nose of the shuttle. Leaning columns and shadowy, submerged structures, set in precarious shapes by the extreme cold, formed a lattice of obstacles for the servitor-pilot to negotiate.

The light became paler as the shuttle ascended. An undersea shelf composed of drifts of silvery machine-shavings rolled out of the gloom - where it broke the surface was a shining horizon, the beach on which the shuttle would land.

Perhaps the shuttle had already been spotted. Perhaps combat servitors were writhing their way through the ocean or were waiting for the shuttle on the shore, ready to turn the liquid hydrogen into a localised, short-lived inferno that would incinerate the shuttle and crew. But these were the risks you took when you tangled with the Adeptus Mechani-cus head-on.