The fire door blew open. Huge chunks of fibrous matter dirtied the air. One struck the Doctor on the back of the head, and hurled her into the console. They both went down with a crash and clatter.

‘Doctor!’ Graham shouted, appalled. But already, equine heads and glowing red spears were pushing through the shattered doors.

Two sets of dark alien eyes fixed on Graham and Ryan. One of the creatures pushed through, heavy and powerful, its armour gleaming in the low-level lighting. It glared down at the Doctor and pressed a button on the girdle around its humanoid waist.

‘Cardiovascular activity ceased. Life signs extinguished.’ It cantered round to where Graham knelt, speechless, clutching Ryan’s unconscious form like a child with a teddy. The centaur thing loomed over him.

‘You are property of the Astingir,’ it said, and nodded its long head to its fellow. ‘We will take them to the War Chariot.’

The Doctor woke with a cry and found the station around her was screaming too. The hot air smelled of smoke and waste and decay. She put a hand to her chest, felt the skittering heartbeats; it was a long time since she’d shut down her cardiovascular system. Shock of the impact perhaps, or just instinct – knowing who it was who’d blasted through the fire door.

‘Still got it,’ she muttered, getting woozily to her feet, wincing at the feel of the bump on the back of her head.

What she didn’t still have was Graham and Ryan. Besides her and the TARDIS, the room was empty.

‘No,’ the Doctor muttered, staring around. ‘Oh, no …’ She shrugged on her soot-smeared coat, climbed through the split and oozing fire door and staggered off down the corridor. The station lurched to one side, and she fell against the wall. A vile brown fluid was dribbling down from the ceiling. Particles in the air sparked and spat around her like hot fat, in a light show that was both beautiful and frightening.

She kept stumbling along the corridor. ‘Ryan!’ she yelled, ‘Graham!’ and the dying ship seemed to groan back at her. The floor beneath her suddenly gave way and she clutched at the rotting walls to stop herself falling through to the floor beneath.

‘This is hopeless.’ Clawing her way back up, she had to close her eyes as dizziness swept across her. Then she heard a voice calling to her, distorted through the bowed corridor, back the way she’d come. A man’s voice. ‘Graham?’ she yelled. ‘Ryan, is that you …?’

But it wasn’t. As she staggered back to the collection point, the Doctor realised the voice was coming from the TARDIS. It was Will.

‘ … for God’s sake, somebody come in, please, over.’ A pause, the crackle of static. ‘Look, if you need a rescue mission it’s no good, that station will be gone before I can get to you, over.’