Kerys halted only paces from the officer. Still that weapon didn’t waver, though its muzzle was only a hand’s breadth from Kerys’s chest. And still the officer held her place, though the fear and uncertainty were obvious in her eyes. Kerys felt a stab of sympathy, and shame at what she had to do.

She made sure the officer had seen her own shoulder flashes, and recognised her rank of nauarchus. Then she switched her communications to a standard channel and snapped, ‘Your name?’

‘That is irrelevant, nauarchus. With respect. Our orders – my orders – were to secure this vessel against intruders. And—’

‘Your name,’ Kerys repeated silkily. ‘You see my uniform. What harm can it do to tell me your name?’

‘Gerloc,’ she said at last. ‘My name is Gerloc. I come from Atrebatu, which is—’

‘I don’t care where Atrebatu is. So, Gerloc. I can see you’re a druidh.’

‘Yes. My Navy rank and druidh level are—’

Kerys waved that away. ‘And you’re a Navy officer. This is a Navy vessel.’

‘Yes, nauarchus.’

‘You say your orders were to secure this vessel against intruders.’

‘Yes, nauarchus.’

‘Very well.’ Kerys glanced around, deliberately casual. Then she forced herself to scream in the girl’s face. ‘And do I look like an intruder to you?’

‘No! I mean, yes – nauarchus.’

‘Did you not hear the instructions my ship broadcast?’

‘Yes. But we had no orders concerning your arrival. The Roman ship that brought you here, we had no clearance, and then your descent on the wings without calling ahead—’

Kerys deliberately backed off. She said more calmly, ‘Have you never heard of a snap inspection? What use would that be if my arrival was heralded in advance, as if I was some pompous Caesar returning to the fleshpots of Rome?’

The girl didn’t budge. ‘But, nauarchus—’

Kerys held a hand to the side of her helmet, and the other palm up. ‘Hush. Can you not hear that? That’s your own trierarchus giving me clearance. You’re to stand aside. Aren’t you getting it? Maybe your equipment is faulty.’

Gerloc lifted her free hand to her own helmet, and with a troubled expression glanced away from Kerys.

That moment was all Kerys needed. She stepped inside the arc of the weapon, grabbed Gerloc’s helmet with two hands, and yanked it forward. The back of Gerloc’s head clattered against her helmet, and she was immediately rendered unconscious. Kerys carefully lowered her to the Martian ground, while behind her Freydis hurried forward to collect Gerloc’s weapon.

‘That was kind of you, nauarchus,’ Freydis said. ‘Relatively.’

Kerys knelt over the girl. ‘I hated having to do that. This one stood her ground while the rest of the idiots around her went running off in pursuit of glory. Stood her ground in spite of all the pressure I could bring to bear on her. She had her orders, and she obeyed them, and this is her reward, from me, her commanding officer. At least I was able to spare her a broken nose or a few lost teeth.’

Freydis looked up at the sky. ‘Nauarchus, maybe we’d better get moving. That thing in the sky isn’t slowing down any.’

‘Too true. Come on, Freydis. Keep your weapons ready. Try not to kill, but if you have to—’

‘I can see there’s a greater good, nauarchus.’

‘There is indeed. I want this bucket to be off the ground in an hour, or less.’ She looked down at the inert body of Gerloc, who looked as if she was peacefully sleeping. ‘Help me haul her aboard the Celyn.’

‘Of course, nauarchus. Umm – why?’

‘Because she may have a better chance of survival aboard than if we leave her here. She deserves that much. But bind her hands and feet, in case her sense of duty gets in the way again.’

‘Yes, nauarchus.’

Glancing over at Freydis, Kerys saw that Höd was actually casting a shadow now, from the soft features of the woman’s young face, behind her visor. ‘Let’s hope, in the end, that all our heroics aren’t necessary after all … Come on, let’s get on with it.’

Eilidh, piloting the small kernel-driven landing yacht bearing her fractious and complicated companions, was ordered to descend to the third of the surface complex’s compounds, centred on Earthshine’s heavy bunker. But she wasn’t to land until the operations at the tree and at the Celyn were well under way, the guards drawn off. So after she had guided the yacht through its entry into the Martian air she hovered, waiting for a final confirming order from Quintus Fabius, who watched from the Malleus Jesu.

Mardina, surrounded by her family and companions, carefully followed the progress of the military operation on the ground. It wasn’t just that her life depended on its outcome. She was actually interested in it, the first genuine action she had ever been a part of.

She felt she was learning constantly, not least from Quintus Fabius and his officers as they had studied this strange surface target, and he had improvised his plan of attack. Nothing specific about that, she thought, could ever be taught in an academy, or on a training ground, or even on manoeuvres out in the field. All training could do would be to leave you with a certain suppleness of mind – suppleness, wrapped around a bony core of determination. Quintus Fabius had never lost sight of the ultimate goal of this operation, for all its confusion and complexity: to find a way to stop the ice ball, Höd, hitting the planet Mars, if he possibly could.

And now here she herself was, involved in this horribly ambiguous part of the operation herself. She was glad to be involved in the action. But she wished she was doing something simpler! Morally clearer! Even if more dangerous. She would have loved to bowl across the surface of Mars with Titus Valerius in his testudo, firing missiles at the sacred giant tree, or to storm that waiting spacecraft with Kerys and Freydis …

Not that there wasn’t danger enough in her own assignment. The yacht was broadcasting continual identifying messages, and images of the craft’s occupants: crucially, the faces of Beth and Mardina. All this was an attempt to get through to Earthshine, to persuade him to let them through. Fine. But it was all terribly flaky. They were so exposed in this yacht, hanging here in the air. It only needed a few of the ground troops to behave in an unexpected way – in fact, to follow their orders – and it could all go wrong. Mardina herself had watched as one lone officer had stood by her post at the spacecraft, the Celyn, and held up the nauarchus Kerys.

Worse than that, however, was the fact that in this fragile little ship Mardina was stuck with her family, among other lunatics. Her mother Beth, who could hardly bear to look at her father Ari. The strange slave boy Chu Yuen sitting as ever in his submissive posture, eyes averted, his pack containing the mysterious machine Collius cradled in his lap as if it were the most precious treasure in the world – well, Mardina supposed, for him it was, as it was probably all that kept him from being cast down into some even worse situation than this. And, to complete the party, here at her own insistence was Academician Penny Kalinski, a woman who Mardina, her former pupil, was very fond of – but she was so hopelessly old. What was Penny doing descending into a combat zone with an asteroid about to be dropped on her grey head?

This strange crew, all save Eilidh at the controls, were strapped into couches set in a rough circle in this small, cramped cabin, all facing each other, all trying to avoid the others’ eyes.

But at last the message came from the Malleus that they were clear to land.

It was Stef Kalinski who spoke to them from the ship. As the operation had sorted itself out, she had volunteered her services to Quintus Fabius as capcom for the yacht, as she put it, a strange pre-jonbar word that nobody understood, except possibly Penny. Now her voice called clear and strong from the speaker. ‘We finally got word from the bunker. Earthshine can see you. He says you’re free to land. You should see a docking port, suitable for ships of Roman, Brikanti or Xin design. Take her down when you’re ready, Eilidh.’