The hole was more of a low passageway, widening almost immediately after they entered it, so Albert found it fairly easy going, apart from the fact that he couldn’t see anything. But, by keeping his arms stretched out to feel the walls so that he didn’t lose his bearings in the dark, he made good progress, until he began to see a faint light. The light grew larger and he emerged into yet another tunnel.

There they waited for everyone to come through, which they did presently, even Kieran, who looked extraordinarily relieved to be out of the hole.

‘Follow me,’ said Marcus, turning and walking down the passageway.

The tunnel stretched on and on before narrowing and sloping downwards, with even more twists and turns than the last one Albert had been in. This one had no lanterns on the ceiling, but a row of small holes in the roof let in a pale, blue-green light from somewhere above, so the effect was quite similar in a sickly sort of way. There was even an illuminated corridor, framed by darkness. Even so, he still found it painful going. Then the passage took an sharper downward slope—it was like descending a hill. The path was complicated by all the spurs and spikes of rock and mineral jutting out from the walls, floor and ceiling at strategic angles, waiting to snag your coat if you were lucky, to jab, scratch and perhaps even provide you with additional orifices if you weren’t. He was fast realizing that the best thing to do was to keep an eye on the person ahead of you and learn from their misfortunes. Since he was walking in the middle of the group, in his case that person was Theo, which defeated the theory somewhat—she was small enough to pass under and through many obstacles that, seconds later, would maliciously compensate for her escape by extracting their pound of flesh from him.

Ahead of Theo, he could see June. She seemed to be finding it easier going than he, but it was clear she was far from having a good time. Colby and his men brought up the rear of their little procession, and he couldn’t help but admire the practised ease with which they negotiated the difficult terrain, always seeming to know exactly the right place to put their feet. But even with all their proficiency they couldn’t begin to compare to the man called Marcus.