I leaned limply against the wall, my ears cocked, while I struggled to control my laboured breathing. The pattering sound had died away, but I knew we wouldn’t have more than a moment’s respite.

‘We’ve got to keep moving.’

Away in the distance, the pattering sound began again. Paula staggered unsteadily to her feet.

‘Come on,’ I said and, supporting her, went forward at a staggering jog-trot.

After a while she got her second wind, and we began to run again. The sound behind us had become ominously close. Somehow, probably spurred on by the squeaking and pattering behind us, we managed to increase our speed. We came to another intersection and without pausing to think, I swung right, dragging Paula with me. We pelted down a long, high tunnel.

Ahead of us the tunnel began to narrow. I flashed the beam of the torch to see where we were going. Before us was an archway, no more than a hole in the wall.

‘In here,’ I panted, pushed her through the archway and staggered in after her.

We found ourselves in a big, lofty cave. As I swung the beam around, lighting up the walls, I saw a great pile of wooden boxes standing in the middle of the cave.

Paula cried, ‘There’s no way out, Vic!’

She was right. We had blundered into a cul-de-sac. There was no escape now. We couldn’t go back. The rats were already rushing down the outside tunnel.