Tycho Station was built like a ball half a kilometer across. The construction sphere was big enough to accommodate almost any ship smaller than a battleship in its interior space. At rest, the two rings at its equator gave spin gravity to a city’s worth of the Belt’s best engineers and technicians. The great drives at the sphere’s base could move the station anywhere in the system. Or out of it, now. Tycho had overseen the spinning up of Ceres and Pallas. It was the beating heart of the Belt and its loudest boast. The Nauvoo, the ship that would have taken humans to the stars, had been too large to fit inside the construction sphere, but it had been built in space next to the massive station. There was no better place for the construction of grand dreams than Tycho. Along with the terraforming of Mars and the farms of Ganymede, it was a living testament to humanity’s ambition and skill.

Holden would never have imagined it could feel fragile.

The transfer from ring to construction dome was like taking a particularly awkward lift. They began at the full one-third g of the station, lurched, and their weight began to leach away. When doors opened again, they were in free fall. The blood that had started dripping from Fred’s arm was a fluid coating now, the liquid held to his body by surface tension as it gradually thickened into a kind of jelly. Garret was covered with it. Holden was too. He kept expecting Fred to pass out, but the old man didn’t lose focus or determination.

Visible from the long translucent tube of the access corridor, the construction sphere looked like a network of purified functionality. Other corridors curved between the ship berths, the walls tiled with a subtly repeating pattern of access panels, power transfers, storage and equipment lockers, and mech parking plates. The steel and ceramic bones of the station showed everywhere, and the light was as bright and harsh as sunlight in vacuum. The air in the access corridor was sweet with the scent of carbon lubricant and electrical discharge. Together, the three of them pulled themselves headfirst toward station south, the engineering decks, and the massive fusion reactors. Holden’s body couldn’t decide if he was falling down a long, bent well or swimming along an underground river of air.

“Drummer!” Fred snapped. “Report.”

The audio feed from his hand terminal was confused for a moment, then the woman’s voice came, her syllables clipped, calm, and measured in a way that sounded like the professional version of raw panic.

“Understood. Main engineering has been shut down by the hostiles. They are holding auxiliary engineering with a force of approximately twenty well-armed enemy, sir. We’re in a mutual holding action.”

“Can you disengage?”

“Not safely, sir. They can’t move, but neither can we.”

“Do we know —”