The contorting empyrean sent another huge wave slamming against the Red Tear. The flagship groaned. It heaved to port like a terrestrial ship caught in a swell. The artificial gravity could not adjust. It was fooled by the madness of the warp, and when the deck canted violently, officers and servitors slid from their stations towards the port wall. Another wave hit, this time from an imagined below, knocking the prow high. The huge vessel tossed and dropped, a leaf in a whirlwind. The mechadendrites of the command throne linked Carminus to the ship’s guidance systems, and he bellowed orders to the secondary guidance operators. They were fighting to right the ship in a realm where space was meaningless, where all directions were none. But even a substanceless dream can be fought, and the immaterium had substance. It was more and less than matter, and it was hostile. It was a foe to be fought as much as the dark ship.

His jaw clenched, Carminus brought the Red Tear to a level bearing, directly in the wake of the huge vessel. The battleship gave chase, and behind it, the rest of the fleet moved into formation. Sanguinius listened to the messages as they came in. Numerous ships were still struggling with daemonic incursions, but no helms had been lost, and even the Chalice, the most hard-pressed by breaches, managed to join up.

‘We’re going faster,’ said Mautus.

‘That is an illusion,’ Sanguinius corrected him. He understood the misperception, though. The ship did seem to be running more smoothly. The wake of the enemy was calmer, and the stuff of the immaterium appeared to be hurrying the Red Tear forwards, as if millions of spectral hands were hurling the vessel along its destined path.

And illusion or not, the conceptions of speed and direction were the only ones available.

‘Range to the enemy?’ Sanguinius asked.

‘No closer than before,’ said Mautus.

Far from ideal. Only now the entire fleet was pursuing the target.

‘All ships, open fire,’ Sanguinius said. ‘Destroy that phantom.’

The XIII Legion fleet lost two destroyers on the first jump. The cruiser Praetorian of Ulixis vanished in the warp during the second. By the third, almost a quarter of the fleet was reporting episodes of madness afflicting Navigators. Guilliman ordered the fleet’s formation held even tighter. The risk of collisions was high, but he was willing to take it. The communications were better, and the diminished isolation of the ships was a lifeline of sanity to the crews and struggling Navigators.

The practical worked. But as the Samothrace shuddered its way through the warp, the measure felt inadequate. The tempest of the immaterium clawed at the ship. The decks and walls groaned with the strain of holding fast to their reality. Nightmares pressed at the hull, seeking purchase, seeking entry. The Geller field was holding, though the air Guilliman breathed felt wrong, as if tainted by invisible filaments, a twitching nest of insect legs.