Hold them … Again, Ace felt the spectral touch of the Wraiths clawing through her flesh and bone to mark the soul inside. ‘Professor … they held me. I can still feel the touch of them. Burning. Like a brand.’

‘I’m so sorry, Ace.’ The Doctor offered his hand to help her up. ‘I didn’t think—’

Ace ignored the hand. ‘Tell me why you brought me here, Professor. It wasn’t just to check up on things, was it?’

‘Time to leave.’ He glanced anxiously behind him. ‘Once we’re back in the TARDIS, I’ll—’

‘Tell me!’

‘Because there’s no such thing as an ultimate weapon, Ace. Or an ultimate prison, for that matter.’ The Doctor looked pained, now, wringing his hands. ‘One day the Wraiths may find a way out of this trans-temporal hell they’ve been caught in. You think they won’t want revenge, that they won’t wage war on the cosmos again?’ Again, more forlornly, he reached out to her. ‘On that day someone who can interact with them would make a useful … emissary.’

Ace met his eyes, got up by herself. ‘And now they’ve touched me, I can do that? Interact?’

‘You must believe me, if I could’ve done it myself, I would have. But I’ve crossed the time fields in the TARDIS too often, I’d slip through their fingers.’

Those long, sharp fingers, scratching her … Ace felt a kind of icy calm damming up her darker feelings. ‘So you needed someone rougher round the edges. Someone who has form dragging others between worlds, the way I did between Earth and the Cheetah planet …’ She got up. ‘Someone whose first trip through time and space was the hard way, through a time-storm …’

‘Ace, it was only a precaution. You know we must be ready for evil to strike at any time—’

‘It’s you who strikes! And always at me.’ Ace turned and stalked away. ‘I can’t believe I let this happen again. Let you keep me in the dark and—’

Another crash cut short her temper. The Astingir had galloped round the ruins and a broken spire came toppling down as they passed. Pointed ears flattened to their equine heads at the sight of their prey, they charged forward and raised their golden bows and arrows.

‘Run!’ The Doctor shooed Ace like a chicken. ‘Higher ground, the more rubble the better, it’ll slow them down.’

Ace nodded. That at least made sense; the Astingir were faster than Cheetah people, mount and warrior in one, but the human form was better for climbing. She made for a large boulder blocking the path ahead. A laser shaft went shimmering past her head and half the stone blew apart, peppering her with shrapnel. She and the Doctor scrambled over it, and had scarcely reached the other side before the rest of it was cracked in two by a volley of blazing arrows.