It was a similar story when trying to get back into realspace. If the plasma engines fired whilst inside the Geller effect, the recursive nature of the reality bubble might redirect the plasma flow back onto the ship, or the Ithraca’s Vengeance could rip its way out of its own protective capsule. However, some relative motion was required to give traction through the translational space between the warp and realspace. Usually this was provided by the action of the warp itself, the currents that the Navigators used to approximate spatial motion whilst traversing a dimension in which neither time nor space really existed. Without the motion-equivalent of the warp the only movement that could be used was the diminishing inertia of the ship itself. Even though the warp was almost wholly flattened, there was just enough granularity of it remaining to act like friction on the passage of the cruiser’s Geller field. The effect was unpredictable and the time to translate back into realspace was as much a matter of instinct and experience for Kosa and her cousin as it was a calculable phenomenon. If the return to realspace was too late, they would bounce off the Impossibility Boundary – as the tech-priests had called it – and slowly drift to a halt in warp space, stranded until such time as the currents returned. On the other hand, even shortening a jump by a couple of light-weeks added to the overall number of jumps they would have to make before reaching tractable warp space again. Praxa­medes disliked guesswork but had stopped trying to understand all of the intricacies of the physical meeting the metaphysical, and like the captain, now relied upon naked trust of the tech-priests and Navigators.

If they got their calculations wrong, there was nothing the Space Marines could do to resolve the errors.

Watching the chronometer approach the Zero Instant, the lieutenant wished he had not dwelt on their predicament so long. The slingshot jumps lost their veneer of mundanity when he thought properly about what they were doing. The risks they faced with each jump were not the kind that were mitigated by practice. Repetition simply increased the chance of an oversight or mistiming.

He cleared his throat and announced the one-minute mark to Zero Instant.

‘Warp engines ready.’

‘Preparing diversion to Navigator control.’

‘Geller field is nominal.’

Other acknowledgements echoed back across the strategium. Captain Aeschelus stood at the command throne, fists clenched at his sides, watching the star-filled display as though the empty void might betray some secret of what was to come. Or perhaps it was pure frustration that clenched the captain’s jaw. The star centred in the read-outs was Casparill, their destination. After twelve jumps they had covered nearly three-quarters of the distance.

Four more jumps. Perhaps five.