Halogi-Kari placed his hand to the door and it swung inward, soundlessly – to reveal another door, this one with a blue hue to the thick steel. Again, it opened, to reveal another behind it. ‘The safeguards are many,’ he said. ‘They have to be, do you see? Such energies I have released …’

Ace was starting to feel them now. A tingling inside, like little tongues dipping into her veins, a stirring in her senses, awakening higher senses she’d never known she possessed. Her limbs began to twitch. She felt dizzy.

As Halogi-Kari opened yet another door, one that was deep crimson in hue, powerful light and heat radiated out from inside. Ace knew that these sensations were just the tiniest, throwaway hints of the energies’ true properties, the first clumsy taps of some unknowable creator’s chisel on the dull stone of her human senses.

In the space beyond the door, Ace slowly perceived movement. A dark, skeletal shape, stalking through a white void, flickering.

A Wraith.

She heard the Doctor’s voice echo in her head from long ago: ‘One day the Wraiths may find a way out of this trans-temporal hell they’ve been caught in …’

‘These poor creatures,’ said Halogi-Kari. ‘Out of the Anvil, the Wraiths have no way to interact consistently with reality any more. Only here, in this no man’s land I have built where the abstract and physical meet, can they function. But it is little more than the sticky paper that holds the fly stranded in mid-flight until it dies. In order to move on, to escape, reality must be re-imposed on the Wraiths.’

‘You think they won’t want revenge?’ the Doctor had cried. ‘That they won’t wage war on the cosmos again?’

Dimly, Ace perceived other shapes. Sharp, sleek robotic creatures, hovering, circling, flicking out tendrils of liquid metal into the Wraith’s flickering, fragile form. One of them held something. Ace had the ridiculous image for a moment of an assistant in a clothes shop, hovering behind a customer with a new suit to try on. A blood-red suit, blurred and indistinct.

‘As the Wraiths’ cellular stability warps and wends, only living organisms can anchor them in reality.’ Halogi-Kari smiled at her from beside the door. ‘Living creatures have a fixed relationship with time, you see? They are born ageing, moving inexorably towards death. That steady tick, tick, tick of life’s clock, the complex chemical kinetics of organic decay … with a certain amount of technical assistance, these can be absorbed by the Wraiths, helping to stabilise their fractured forms.’