‘What, run, you mean?’ asked Bel.

‘Yeah,’ said Amy. ‘Can we just save me some time and take it as read from now on?’

A second Ice Warrior plunged like a boulder from the bridge above. It landed behind the first, missing the main platform, but impacting, as Arabel had done, against the guard rail. Pincer clamps snapped shut around the rail to prevent it from toppling backwards into the drop. The metal railing was buckled and twisted by its collision.

Slowly, clumsily, it clambered over the bent guard rail and onto the bridge. There, it unfastened the battleaxe anchored across its back, and set off after the first.

Amy was just a short distance from the safety of the hatch. She reached out her hand so she could touch the palm-checker plate as soon as she arrived and open the door. If they could get through and close the hatch again, the Ice Warriors would have to stop to drill the lock out, and that would buy them a little more time.

The hatch began to open. She hadn’t touched the plate. Something on the other side had activated the lock system.

Amy slid to a stop, and Bel and Samewell cannoned into her from behind. All Amy could think was the Ice Warriors had somehow learned how to work the locks.

Something came through the hatch and out onto the bridge facing them.

It wasn’t an Ice Warrior.

The three of them screamed anyway.

‘Do you know what I’m going to do?’ the Doctor asked Ixyldir. ‘I can’t believe I’m saying this, but do you know what I’m going to do?’

‘What?’ asked the Ice Lord.

‘I’m going to help you,’ the Doctor replied.

‘Help me?’

‘Help you all. There’s a level to this situation that neither of us really anticipated.’

‘I do not believe you can be trusted,’ Ixyldir replied.

The Doctor shook his head, and snatched the communicator pad out of the Ice Lord’s grip. Ssord and two other Ice Warriors reacted to stop him, but the Doctor did a little duck and weave to avoid them as if they were the least of his worries. He was busy examining the pad’s display.

‘You’re taking a pasting, Ixyldir,’ he said, reading data. ‘Your slow, cold war has turned into a fast, hot one. This is not what you were expecting at all, is it?’

He looked at the Ice Lord.

‘Is it?’ he repeated. ‘I’m not saying that you’re not prepared to fight. You’re Ice Warriors, for goodness sake. But this isn’t the scenario you were expecting when you began your offensive ten years ago. Is it?’

‘No,’ said the Ice Lord.

‘Escalation,’ said the Doctor. ‘You said it yourself. I can help you, but only if you start cooperating with me quickly. I mean very quickly. We don’t even have to trust each other completely, but if we don’t get this situation under control, there are going to be an awful lot of deaths. Morphan, Ice Warrior. Unnecessary deaths. This world laid waste, possibly to the point where it is of no use to either colonial effort. Come on, Lord Ixyldir of the Tanssor clan! Be smart!’

The Ice Lord seemed to take an eternity to reply.

‘What form would this cooperation take?’ he asked.

The Ice Warriors behind him swung their heavy heads to glance at one another.

The Doctor grinned.

‘That’s the spirit, Ix! That’s the spirit! You’re starting to thaw, pardon the pun! This could be the start of a beautiful friendship, Ix! Can I call you Ix?’

‘Most certainly not.’

‘Well work on that, then. Here’s what I need first.

We have to find another facility like this, this telepresence communication centre.’ The Doctor gestured to the chamber they were standing in. ‘Ssord’s handy axe-work rather ripped the stuffing out of the systems here,’ he said. ‘I could fix it, but it would frankly take more time than we have at our disposal.

There must be another. You’ve been working your way through this complex for years, cutting open doors.

You must have found another one or two by now.

Preferably, a more significant control room than this.

This is just a secondary station. Do you know of any primary command and control rooms?’

Lord Ixyldir looked at Ssord.

‘Level sssix,’ the Ice Warrior hissed.

‘Let’s go!’ the Doctor cried. ‘Lead the way, Ssord.

Lord Ixyldir, we’ll walk and talk.’

Ssord led the way out of the chamber. The other Ice Warriors fell in around the Doctor and Lord Ixyldir as an honour guard escort.

‘Walk as fast as you can!’ the Doctor urged. He looked at Ixyldir. ‘I need to know the details of your operation,’ he said. ‘It’s vital. On several other occasions, I’ve known your people to instigate terraforming processes on target worlds. You’re pretty good at it.’

‘When our migration fleet entered this quadrant, this planet revealed itself to be the most likely candidate for adjustment,’ replied the Ice Lord. ‘Long-range observation confirmed it met the majority of our colonisation criteria. We resolved to achieve orbit, to commence climate engineering, and then wait for the process to be completed by entering hibernation on our ships.’

‘Were you planning to use seed technology to bring about climate alterations?’ asked the Doctor.

‘You are familiar with the technique?’ asked Ixyldir, surprised.

‘I’ve stopped it more than once, actually,’ the Doctor said. ‘It’s very efficient, though. The destabilisation of carbon dioxide levels is often all it takes to induce a global arctic phase on an M-class world.’

They left the gloom of the tunnels and followed a broad, railed walkway around the edge of a plunging turbine cavern.

‘Once we were in orbit,’ said the Ice Lord, ‘we realised that a human colony was already established on the candidate planet. It had been here for some time and, though comparatively small, it had constructed terraforming processors of significant size and effect.

This process had been under way for several generations, and was already beginning to induce change.’

‘So you thought, “Why bother setting up our own terraforming programme to work in opposition? Why not just repurpose the one that’s already there?’”

‘This was deemed to be the most viable option.’

The Doctor shook his head sadly. ‘This is where you and I will be forced to disagree, Lord Ixyldir. That was a pretty underhand gambit. You decide to steal a planet out from under these settlers, you coopt their terraformers to do the hard work for you, and you essentially consign them to a generation or two of long, slow, bitter extinction. You signed their death warrants, Lord Ixyldir, but you let the snow and ice do the actual killing for you. You didn’t have enough respect for your adversary to pull the trigger yourself.

Dirty pool, Lord Ixyldir. That’s dirty pool.’

‘I do not understand your reference,’ replied the Ice Lord.

‘It’s not very honourable, is it?’ replied the Doctor.

‘That’s what I’m saying. Theft, on a planetary scale.’

‘This was not the humans’ planet either. They selected it and claimed it. We were merely doing the same.’

‘But they were here first, Ixyldir. It’s a bit of a school playground he said, she said argument, I know, but do you know what? Most honour systems are built on very simple, basic concepts of ownership, or respect, or prior claim, or of precedence. The humans were here first, Ixyldir. You decided they were in the way, and you decided to steal their technology to eradicate them. Don’t talk to me about honour.’

‘It was a matter of survival,’ objected Ixyldir.

‘Ah yes, the famous pragmatism of the Ice Warriors.

You didn’t mean to hurt anybody, but you were obliged to in order to survive. Lord Ixyldir, the deliberate and systematic eradication of an entire population is called genocide, and it’s not regarded as especially honourable either. Not where nice people come from.’