Chapter 12: The Underground Heating Core
The snow was coming down harder when Duvette left the command post.
Fine flakes turned in the wind like grey moths falling to earth. The artillery exchanges that had been audible from the horizon were completely silent now. The whole world had gone still. The only sounds were the compression of snow under boots and the wind moving through the empty streets.
The operations briefing had run for two hours. Colonel Fox had not excluded him on account of the recent promotion. He had been present for the full session, standing at the map table with six other officers, all of them wearing expressions that matched the sky outside.
The Imperial forces on Farrak IV totaled approximately one hundred and sixty thousand soldiers across multiple regiments: the Ash Watchers, a Cadian Armoured regiment, the Valhallan Ice Warriors, the Mordian Iron Guard, and several others, all under the unified command of a Lord General.
The Heras defensive line had been absorbing intense cult assaults for weeks. Three days ago, the attacks had stopped entirely.
Not just here. Reports from across the theatre showed the same pattern: the cult had reduced its offensive pressure almost simultaneously across the entire planet. Initial assessment from command had attributed this to the cold snap. At minus forty degrees, sustained offensive operations would be genuinely difficult for any force without special equipment.
But Duvette's notebook, the presence of a Chaos Astartes in the tunnel network, and the intelligence about the interconnected underground passages below the city had shifted that assessment considerably. The officers around the table had gone quiet in a particular way when the full picture had been laid out.
The enemy had known the freeze was coming.
They had planned around it from the beginning.
The tunnel network was the second concern. The unexplained flanking attacks, the units appearing on the wrong side of defensive lines, the ambushes that materialized out of nowhere over the past weeks: all of it now had an explanation. The cult did not need to move on the surface. The underground passages ran everywhere.
During the period of Duvette's unconsciousness, the regiment's reconnaissance teams had found seven additional underground ritual sites. Combined with the consistent reports from frontline soldiers of ongoing cult ceremony activity, the command element had arrived at a conclusion that no one at the table wanted to speak aloud and all of them were thinking.
The enemy was preparing for something on a large scale. A Warp incursion.
The question was where and how.
Duvette had contributed the one piece of direct information he had. He described the junction in the tunnel, the left passage that had produced a physical reaction in him even after Emperor's Gaze had expired. The headache. The nausea. He described it as precisely as he could remember.
Colonel Fox had listened, said nothing for several seconds, and then nodded.
"I will pass this up the chain," Fox said. "Go back to camp and rest. Your wounds are not healed."
Duvette had not argued. He needed the rest and his back was making itself heard through the bandaging.
He walked along the snow-covered road toward the rear. The regiment's camp was in a factory complex not far behind the defensive line.
As he entered the complex, a familiar figure appeared ahead.
Evan.
The boy was wearing a grey greatcoat that was considerably too large for him, the sleeves rolled up enough times that his hands were visible. He was carrying a tin bucket of supplies, stepping through the snow with the careful uneven gait of someone navigating uncertain footing. Snow was settling on his blond hair and on his shoulders, turning him into something that moved between resembling a soldier and resembling a snowman.
"Evan."
The boy's head came up fast. His eyes found Duvette and lit up. He lifted the bucket and moved through the snow at a jog, stopping in front of Duvette with a wide, relieved expression.
"Sir! You are awake!"
Duvette nodded and put a hand on the boy's shoulder. "Thank you for that melta bomb. Without that throw, none of us would have come back."
Evan's face went red. He scratched the back of his head and snow scattered from his hair. "To be honest, I was... I was terrified. I didn't think about it that much."
"You did exactly the right thing." Duvette kept his voice even. "You saved everyone."
They walked together toward the barracks. Duvette asked why Evan was here rather than at the refugee center in the city.
"The center is full," Evan said. His breath came out white in the cold air. "Colonel Fox heard what I did for you and Sixth Company and told me to bring my sister to the regimental camp. He said there would at least be heating here."
Heating.
The word hit Duvette like a prod from a las-lance. He stopped walking.
Evan took two more steps before he noticed Duvette was no longer beside him. He turned back, looking at the commissar standing still in the snow.
"Sir?"
Duvette did not answer. His mind was already moving.
The hospital had heating. The command post had heating. The barracks had heating. Were all those systems independent? No. A city this size could not run on independent boilers for every building. A city this size had one source.
"Evan." Duvette's voice had changed register. "You said the camp has heating. Where does the heating come from?"
The boy blinked. He had caught the shift in tone and it was making him careful. "It's... it's geothermal heating. There's a geothermal heating core under the city. All the buildings draw from it."
A geothermal heating core.
Duvette's pulse was doing something noticeable. He held Evan's gaze and asked the question one word at a time.
"The underground passages. The ones connecting all the cellars to each other. Can they reach the geothermal heating core directly?"
Evan's brow came together as he thought about it. Snow settled on his eyelashes.
"Under normal circumstances, no." The boy worked through it carefully. "The geothermal core and its control room are very deep underground and they have their own dedicated access tunnels. To get there from the cellar network, you would have to come up to street level first and then go back down through the city's official entry points..."
But Duvette was no longer following the answer.
Something was wrong.
What is wrong.
The torn-up rail tracks in the artificially widened tunnel. The skull cairns piled to the ceiling of the grain distribution hub. The final page of the notebook, the line written in blood: The freeze is coming and everything will die. Better to burn as brightly as possible before destruction finds us.
The enemy knew the freeze was coming. They knew about the interconnected tunnel network but had not used it primarily for tactical flanking: they had used it for something else. They had thrown wave after wave of infantry at Heras in costly frontal assaults that achieved very little. They were performing blood rituals in the tunnels at a scale the Astra Militarum had not fully mapped yet.
And the geothermal heating core, if overloaded and detonated, combined with a Warp ritual of sufficient scale, could produce...
"I need to go back," Duvette said. His voice had gone quiet, almost to himself.
Evan stared at him. "Go back where?"
"The command post." Duvette was already turned around. "I need to see the Colonel."
His back wound would not permit running. He walked as fast as it would allow.
The same street, the same warehouse, the same two sentries at the canvas-covered door. The left one looked genuinely confused to see him back.
"Sir? Did you forget something?"
"I need to see the Colonel. Now." The urgency in his voice was not something he was modulating.
The sentries looked at each other. The right one pulled the canvas aside.
"The Colonel is still in the briefing room."