The shadow had fallen across the Enduring Blade and he vowed silently to grapple against it until the last of his energy was spent; a loyal servant of the Emperor could do no more, and was expected to do no less. These ancient warriors, blackened with evil, who had once stood shoulder-to-shoulder with Ardias’s ancestors, these fallen angels; they must be punished.

“Preserve your ammunition!” he voxed, firing off a short burst at one bellowing Chaos thing. A cackling daemon formed from a warp portal at his side and was efficiently cleaved in half by Sergeant Mallich’s chainsword. Ardias nodded gratefully and moved on.

“Brother-captain? This is Sergeant Larynz.”

“Report.”

“I have the third tactical squad, two decks above your position. There are incursions at all points. These portals, brother — have you ever seen their like?”

“Negative. Some dark sorcery lies at their heart, Larynz, you can be certain of that. Courage and honour!”

“Courage and honour!”

“Regroup on my signal, sergeant. I fear we must sacrifice this vessel.”

“Sir? You can’t mea—?”

“Regroup on me, Larynz. No questions.”

“Of course, brother.”

Ardias barged onwards along the corridor, swatting drooling daemonettes like flies. This far into the ship, the walls themselves seemed corrupted— structural damage and ancientness combining with some indefinable alteration to make everything seem organic and twisted. Not for the first time Ardias felt like he was walking in a peristaltic gut, wet walls shivering with hungry villi around him.

“Captain!” the vox chattered, urgently. “I’ve located a communications chamber.” The rust-red shape of Tech-marine Achellus waved to him along a side artery, prominent mechanical appendages emulating the movement of his arms. The figure beckoned into one of the innumerable chambers that lined every corridor, where Ardias could see lights blinking and brass-bound gauges fluttering. In a vessel as ancient and labyrinthine as an Emperor-class battlecruiser, subsidiary control rooms and communication hubs lurked in myriad corners. Given enough time, a seeker could locate any resource aboard a ship of such magnitude.

Ardias strode into the room, nodding at the cob-webbed controls.

“Can you operate them, Achellus?” he asked, perplexed by the endless arrays of meaningless switches and dials.

“By the grace of the Omnissiah,” the Tech-marine nodded, vaguely tracing the shape of the Holy Engine in the air, “I believe that I can.”

“Squad?” Ardias voxed, watching Achellus’s cyborg fingers dancing across the console. “Assume overwatch positions outside this chamber. In the name of the primarch, hold your ground!”

The bolters rattled and the daemons chattered and the hissing, whispering influence of Chaos filled the air with greasy nausea. Ardias bent over the controls, thinking hard, and ground his teeth against the cloying voices in his mind that made it so hard, almost impossible, to lower his bolter and lift a comm transmitter in its place.

“Shas’o? There’s something happening on the battle-cruiser...”

“Is the dropship returning?”

“No... it’s...”

“It’s what?”

“The drones are picking up energy signatures. Weaponsfire, maybe.”

“See if you can raise anyone.”

“Their communications shields are still operative.”

“We can’t reach any of them?”

O’Udas rubbed his temples wearily, feeling exhausted. The return to the primary bridge of the Or’es Tash’var had been accompanied not only with the unpleasant task of removing the smoking bodies scattered thereon, but with the realisation that, lacking a kor’o and having failed to persuade the Aun to remain aboard, responsibility for the vessel and its crew was resting firmly with him.

The kor’el with the unenviable task of filling O’Tyra’s shoes gave him a despairing look. “None, Shas’o. What action?”

None of them had been prepared for this rotaa’s madness.

“They’re taking too long...” he decided, glancing around at the anxious faces, tense bodies perched in ruined seats. “Power up the weapons. No more chances.”

Drones scurried to comply, exhausted air caste personnel tapping at mangled controls, struggling to maintain their professional calm. Udas shared a glance with El’Lusha, rubbing his hands together uncomfortably. The tension throughout the command deck was palpable.

“Shas’o?” a Kor’ui mumbled, frowning. “We’re getting a signal. Very faint but... it’s definitely directed at us.”

“T’au?”

“No. It’s gue’la.”

He nodded, pursing his lips. “Let’s hear it. Branch it to the rest of the fleet too.”

The kor’ui passed a long finger through a sense beam and abruptly a storm of white noise rippled across the bridge, high frequency squeals shifting in tone until a single voice — a gue’la voice — crackled through and resolved.

“—s the Enduring Blade, hailing the tau flotilla. I request acknowledgment... It’s not working, Achellus. Try a different frequency.”

The kor’ui gave Udas a plaintive look. “Shas’o?”

He scratched his chin, tapping a hoof thoughtfully against the deck. A series of tiny drones with flashing “message” icons circulated around his head — kor’os and shas’os throughout the flotilla hurrying to give their advice. He waved them away.

“Open a channel.”

What little white noise that remained on the communication channel resolved with a tinny pop. The ugly gue’la voice halted in surprise.

“Enduring Blade, this is the Or’es Tash’var. Identify yourself.”

“Captain Ardias of the Ultramarines. You must listen to—”

“Where is Aun’el T’au Ko’vash?”

“Never mind that, we—”

“Where is he? We are poised to strike. Return him now.”

“Stand down! You must listen! We face a mutual threat!”

“Lies. Cut the channel. All vessels prepare to engage.” His blood burned.

“Wait, Emperor damn you! The ethereal has been taken — most likely to the planet surface.”

“By who?”

“Chaos, warp take your eyes! Chaos!”

O’Udas frowned. The gue’la’s voice was full of certainty and conviction, as if he was expected to recognise the name of this alleged enemy. The word was delivered with terrible resonance.

“‘Chaos’?” he repeated, unfamiliar syllables sitting awkwardly on his tongue.

The voice replied with heavy exasperation: “Oh, you don’t... I haven’t time to explain. The dark powers! The warp taint! Evil!”

“This is ridiculous. I won’t listen to another w—”

“They’ve taken him and the admiral. We can’t determine how they’re travelling but... listen to me, they are beyond our reach, for now. Attack this vessel and you will waste time and blood that would be better spent purging this threat! We’re under assault.”

O’Udas shook his head, lips curling. “Gue’la lies. Delaying tactics.”

The voice almost roared, a venomous litany of frustration and abuse that pushed O’Udas’s patience over the edge.

“Cut the line,” he growled, directing a pointed look at the kor’ui manning the comms. The channel closed with a sedate peal.

“Shas’o,” El’Lusha muttered from his alcove at the rear of the bridge. “What if he’s telling the truth?”

“Don’t be ridiculous.”

“But if there is a third party involved—”

“We’d know about it. An army doesn’t just spring from nowhere.”

“Agreed but... Shas’o, isn’t it worth investigating? ‘Caution in the face of threat’—is that not the teaching of the Yie’rla’rettan meditation?”

O’Udas breathed out, reluctantly conceding. All this talking exhausted him: his nominal grasp of the gue’la language, coupled with his natural impatience for diplomacy, made him re-evaluate his feelings towards the water caste. He began to wish sincerely that El’Yis’ten hadn’t taken all of her por’ui assistants with her to the human ship.