‘But this one’s grown weak. I thought it had gone, faded away to nothing.’He shook his head with disbelief. ‘I was cleaning up the mess, looking up your files onthe computer, preparing to send myself into the past to find you and bring you back. And allthat time the thing was lurking here in this place… quietly watching me.’

The shape stopped moving. It hovered just a few yards away, a dull pulsating glow that infleeting moments seemed to find a shape that reminded Liam of mythical creatures — acentaur, a unicorn, a dragon — before becoming a pale cloud once more.

‘I’d say it’s too weak to take a physical form. It’s dying. Butwe’re best just keeping back for now.’

‘Does that thing know we’re here?’ asked Maddy.

‘Perhaps.’

Liam licked his dry lips anxiously. ‘Where did it come from?’

‘Another dimension,’ Foster replied, ‘another dimension overlaying ours,perhaps, attracted to the energy of a time portal like a moth is to light. These things areanother reason we should never have messed with time to begin with.’

The entity moved again, this time drifting ponderously towards them.

‘Er… it’s getting closer,’ whispered Sal.

‘Yes, I do believe it is.’

‘But we’re safe, right, Mr Foster?’ asked Liam.‘You said it’s too weak to hurt us?’

Foster’s silence in the pitch black was less than comforting.

‘We should leave,’ he finally replied. ‘We’ve got over thirty hoursbefore we need to return, before the arch’s time bubble resets. I can’t see thisthing surviving that much longer.’

‘Time bubble?’

‘I’ll explain outside. Everyone grab a hand. There’s a mess of things inhere to get tangled in. I need to lead us out.’

Liam, Maddy and Sal reached out and fumbled in the dark, each finding desperate probing handsand grasping them tightly.