Progressive genocide. I’d say that puts you in a difficult place, morally speaking, just to begin with.

Then I arrive, and get caught in the middle, and my actions are misinterpreted as your victims fighting back. Now, in your eyes, it’s a war? You are simply misreading the facts.’

‘And you know more than you claim to know,’

replied the Ice Lord. ‘In this complex, just a short time ago, you addressed my Warriors as you fled from them. Ssord, repeat the words the prisoner used.’

The Ice Warrior with the axe took a step forward. In a compressed air-hiss, he said, ‘The captive ssspoke thusss: “Warriorsss of the Tanssor clan line of the Ixon Monsss family, inform your warlord that the Belot’ssar greetsss him.’”

‘Explain how you know these things,’ the Ice Lord said to the Doctor.

‘It’s obvious,’ replied the Doctor. ‘You are of the Tanssor Clan. The characteristic pattern of scales and ridges on your breastplates and helmets is unmistakable. The emblem on your pectoral confirms that your clan allegiance is to the Ixon Mons family, which is one of the most code-honourable families on Old Mars. It’s a simple matter of observation.’

‘And also a simple matter to conclude that you have encountered my species before,’ said the Ice Lord.

‘I never claimed I hadn’t.’

‘Your knowledge of our culture is considerable. You know how to fortify against our weapons. You understand the lineage and hierarchy of our bloodlines.

You distinguish the polymorphic traits of our physiology, a habit seldom known in other races. And you know words in our language. Belot’ssar.’

‘Indeed,’ smiled the Doctor. ‘ Belot’ssar. I was wondering when we’d get to that.’

‘As I was wondering why you used the term.’

‘It means cold blue star,’ said the Doctor.

‘Curiously enough, I know what it means,’ replied the Ice Lord. ‘Why did you use the phrase in, so it seems, reference to yourself?’

‘Because that’s how I’m known to your people,’

replied the Doctor. He looked quite pleased with himself. ‘Traditionally, I mean. Your people, particularly the Ixon Mons family, know me as cold blue star. It’s a reference to the ship I travel in. The title is an honorific. It shows me to be a true and lasting friend to the Ixon Mons dynasty, but also a fair and daunting adversary.’

The Doctor rose to his feet. The Ice Lord stood to face him. The Doctor drew himself up, narrowing his eyes to look at the Ice Lord. He was fearless. The gloves were off. It was time to play his ace.

‘I have been a friend to the dynasties of Mars,’ said the Doctor, ‘but I have also been a foe. I have fought them many times and I have won every time. Ice Lord Azylax, warlord of the Tanssor, personally named me the Belot’ssar as a mark of respect, so that future generations would know me and tread carefully. The situation on this planet will end. You will disengage, and you will cease your prosecution of the human population. That’s your final warning. I am everything your ancestors warned you about. I am the Belot’ssar.’

The Ice Lord stared back at him. There was no expression.

‘Never heard of you,’ he said.

‘What?’ asked the Doctor.

‘I am Ixyldir, warlord of the Tanssor Clan,’ said the Ice Lord. ‘There has never been a warlord called Azylax. We know nothing of a respected foe known as the cold blue star!

‘But…’ the Doctor began.

‘Hang on…’ he floundered.

‘That’s just not…’ he added.

He sat down and rested his forehead on his hand.

‘Time travel,’ he murmured. He slapped his palm against his forehead repeatedly, scolding himself.

‘Lets you down every! Single! Time! I have got to learn to set my watch!’

He looked up at Ixyldir and the Ice Warriors.

‘All that,’ he said, gesturing vaguely into the space where he had just been standing, as if to encapsulate his bold and defiant performance. ‘All of that showy-offy stuff, could we just pretend that never happened? I can see from your faces that we can’t. You’re going to kill me.’

‘You were going to die anyway,’ replied the Ice Lord.

‘Yes,’ said the Doctor, ‘but now I’m going to be really annoyed when it happens.’

‘We’ve got to go back!’ Amy raged, fighting against the firm grips both Samewell and Arabel had on her.

And do what, precisely?’ Arabel asked.

‘Save him!’ Amy blurted. ‘Rescue him! Poke the Ice Men in the eyes with sticks! I don’t know!’

‘Ice Warriors,’ Samewell corrected her.

Amy turned on him. ‘Oh, really? Really? Now is the time to focus on that? Is it, Samewell Crook? Is it really?’

Arabel pulled Amy away from the cringing Samewell. ‘You’re upset,’ she said.

‘Damn right!’ Amy cried. ‘We just left the Doctor to die! We left him trapped there, surrounded by the giant green lizard things! That’s just… just.

‘Just what?’ asked Bel.

‘It’s not how I do things!’ Amy declared.

She turned away from them. She was breathing hard, trying to control her anger. They’d been running for a few minutes, following an access corridor into a warren of tunnels that had finally led out onto the walkway where they were now standing.

In the vast gulf of the rock-cut cavern below them, huge turbines pumped and rumbled. There was an amber cast to the light. Vapour rose up around the suspended mesh walkway that supported them.

‘He’s always there for me,’ Amy said quietly. ‘He’s always got my back. He’s crossed time and space to save me, more than once. And I just ditched him.’

She turned to face them. Samewell and Arabel were watching her with great concern. Amy held up one baggy sleeve of her duffel coat.

‘Also, I lost a glove,’ she sniffed, ‘which I know is a completely different scale of things to be upset about, but it’s annoying, you know?’

‘He will be all right,’ said Bel.

‘How do you know that?’ asked Amy.

‘Well,’ said Bel, ‘I haven’t known your Doctor for anything like as long as you have. I realise that. But just in the short time I’ve been around him, I’ve been filled with a confidence. He knows what he’s doing.

I’ve… I’ve never met anyone who seems so capable.’

‘Bel’s right,’ said Samewell. ‘The Doctor wanted us to go. He told us to. He was quite plain about it. It was the only way.’

‘Those things, they had us cornered,’ said Bel. ‘He wanted us to escape.’

‘That won’t be much consolation to him when he’s dead,’ said Amy.

‘But it might be consolation to him as he’s dying,’

replied Bel.

Amy breathed out hard. She turned away, gripped the metal handrail and stared down into the pit where the mighty terraforming engines were performing their slow toil.

‘He always has more than one plan,’ she said quietly.

‘How do you mean?’ asked Bel.

‘He wanted us to escape,’ said Amy, turning back to face them. There was a new expression on her face. ‘I mean, of course he did. He was trying to save us, and he’d lay down his life for anyone. But I know the Doctor. He’s like one of those chess grand masters, you know?’

They both shook their heads.

‘They plan their moves way in advance,’ said Amy, carrying on anyway. ‘They know what they’re going to do long before they get there. It was all getting a bit frantic back in that room, and he definitely wanted to save us… and I know there was a lot of improvising going on as well, because I’ve seen what he looks like when he does that. But he always has more than one plan.’

‘So?’ asked Bel.

‘He stayed there so we could get away,’ said Amy.

‘You said it yourself, Samewell, he told us to. He needs us to do something. He needs us to carry on with the plan while he keeps the Ice Men busy.’