Now, thought Cormac, only Arach’s little present stands between them and us. He reckoned those Jain-constructed biomechs could move faster down here than he and his fellows, though they might have to burrow again if there had been intervening rock falls.

‘What explosives do we have remaining?’ he asked.

‘Grenades, eight planar mines and one more CTD,’ replied one of the Golem.

‘Let’s hope we won’t need the CTD,’ he said. ‘Position the mines where you deem appropriate—proximity detonation.’ He added unnecessarily, ‘Let’s keep moving,’ as the water level descended.

Within an hour they left the pipe and ascended a gently upward-sloping fissure. The temperature slowly began to rise, which indicated this cave system opened up somewhere to the surface. Then abruptly the upward slope ended against a wall of stone. Reaching this and directing his envirosuit light upwards, Cormac discerned another fissure climbing up into darkness.

‘How many mines left?’

‘Four.’

‘Okay, you Golem take the lead. Position two of the mines up in the fissure and when you reach a suitable point, run lines down.’

As the Golem headed rapidly up through the fissure Cormac turned to the others. ‘All of you, take a rest.’ He himself felt utterly drained, partly a result of the stimulants he had used while fighting through the jungle above. He did not want to use any more of them until it became absolutely necessary.

Lines snaked down to them twenty minutes later, just as a dull boom echoed through the cave system. The biomechanism must now have entered the underwater cave system. They hooked up their winders and ascended to where the Golem had secured themselves. The fissure here turned to follow an angle of thirty degrees from the horizontal still ascending.

With disheartening regularity over the next few hours the mines they had planted detonated behind them. Twice they needed to stop and take seismic readings to find some available course ahead. Once it became necessary to use one of their remaining mines, then some of the grenades, to blast a way through into another tunnel. While in there another dull boom resounded from behind. Checking some instrument one of the Golem told them, ‘That was the last mine we planted.’ Cormac felt he really did not need that—he could count. Then, manoeuvring through one sharply curving tunnel, he noticed a steady climb in temperature. Further along he found it necessary to close up his envirosuit. Next, reddish light began to impinge.

‘We have a problem,’ came a yell from up front.

Cormac quickly moved up past the others.

‘The seismic scanner missed this,’ explained one of the dracomen, almost guiltily.

The tunnel opened out onto a tilted slab that ran partly along one side of what appeared to be the empty chimney of a volcano. High above, the sky was visible like a bloodshot eye. Cormac moved to the rim of the slab and peered over.

Something down there?