Across the caramelised expanse of the ruined cathedral, Ace saw the first of the Astingir squad burst through the arch. The armoured beast looked like the mutant offspring of a centaur and a horse: a humanoid torso reared up from the powerful white stallion body, but the horse-like head crowning the broad shoulders was no bigger than a man’s. Ox horns speared out from behind the ears, and in its muscular arms it gripped a futuristic bow and arrow that shone with eerie light. It looked both beautiful and horrible as it trotted in a tight circle, perhaps suspicious now its quarries were in sight.

As more Astingir pushed through the doorway, Ace could see what the Doctor had meant about not outrunning them. Their legs looked so powerful, muscles rippling under gleaming metal armour and ash-white hide.

‘You will surrender,’ called the first, in a deep, throaty voice.

‘Will we?’ Ace took a step towards them, her anger making her reckless.

‘No,’ hissed the Doctor. ‘Sit down.’

‘What?’

‘Do it!’ The Doctor turned to the Astingir, raised his hat and gave them his daftest smile. ‘Good afternoon, gentlemen—I mean, gentlehorses. Tell me … why the long faces?’

The Astingir stared, but Ace stared even harder.

‘Seriously, Professor?’

‘Funny. That one normally brings the house down.’ The Doctor plonked his hat back on his head and shrugged. ‘I can see I’ll need a little extra help …’ In a sudden blur of movement, he stepped on Ace’s shoulder and used it as a springboard as he leaped into the air, umbrella raised handle first like a grappling hook. The curved edge of the question mark caught on the brittle beam above as the Doctor swung and tugged.

As one, the Astingir raised their gleaming bows and loosed laser arrows that sputtered and seared through the air about the Doctor, barely missing him.

‘Professor!’ Ace staggered up, as the beam finally broke under the Doctor’s weight and he fell down into Ace’s arms in a shower of carbon fibres. The two of them fell to the floor as more laser arrows snapped and whooshed all around, punching holes in the melted rock.

A deep creaking noise came from the high rafters. With the long beam now broken, the integrity of the roof it had supported for so long was threatened. Already the Astingir were being showered by falling debris as cracks opened in the roof and half-melted buttresses began to crumble.

‘Out of here!’ roared the Doctor, and Ace scrambled alongside him as he made for a nearby doorway. With noise enough to crack the planet wide apart the entire cathedral came crumbling down behind them, the tremors throwing them to the ground.

‘There!’ The Doctor got up and brushed his hands together with satisfaction. ‘No time for a lie down, Ace. That will only hold them back for a while.’