‘Keep running, Ace!’ The Doctor puffed as he ran along beside her, one hand holding his hat on his head, the other clutching his umbrella. ‘If we’re caught here, we’ll be killed.’

She felt a thrill at his words, as ever. The Dalí-esque world of ruins about them was just another arena in which to risk their lives for the good of things: a clear, straightforward flight from the dark to the light. And yet a part of her, still shifted sideways by the Anvil, was wondering, What happens when I get too old to run any longer? The Doctor will go on forever, but what about me?

Again, the image of Earth in the far future, drowning in a chemical slime; again, the burning drive to fight that future, whatever it took.

‘Wait, Ace!’ the Doctor shouted as they ran through a tall doorway into a vast, distorted cathedral. He looked up at the roof, which was still partially intact, supported by struts rising from a long, blackened beam that ran horizontally overhead. With fresh purpose, he led Ace over the cracked glass floor to the far wall. ‘Rest a moment,’ he told her.

‘Why?’ Ace asked him. ‘I thought you said these Aston thingies would execute us.’

‘They will. This world isn’t just Death Row for the Wraiths, but for anyone who dares to visit. There are thousands of proximity sensors in orbit to warn the Astingir of approaching craft, but the TARDIS has always phased through those with ease.’ He frowned. ‘At least I thought she had.’

Ace rolled her eyes. ‘If they’ve picked up the TARDIS coming and going, that would explain why they’ve stuck sensors at ground level too. They want to know what you’ve been up to here …’

‘Excellent reasoning.’ The Doctor’s smile shied far from his eyes. ‘Well, in any case, we can’t outrun the Astingir. We need to use our heads.’

‘Mine is splitting,’ Ace said. ‘Feels like someone stirred my brains with a rusty spike.’

‘Yes, I’m sorry,’ the Doctor muttered, his attention once more on the beam above them. ‘I didn’t appreciate quite how much the Wraiths’ touch would hurt you …’

Ace looked at him. ‘What?’

The Doctor closed his eyes, didn’t respond.

‘What do you mean, you didn’t appreciate how much it would hurt?’ Her eyes hardened, a flicker of fear in her guts. ‘Professor, back at the Anvil when you pulled me clear … you weren’t worried that I’d been touched by those things, were you? You were worried that maybe I hadn’t been …’

Again, no answer.

A sudden rise of anger pushed out her accusation: ‘Weren’t you? Why did we really come here today, Professor?’

‘This is not the time, Ace!’ snapped the Doctor his arms flailing wildly as they always did when he was agitated. ‘Look!’