''So?'' said the Nephthysian, cocking his head to one side. ''Shall we begin?''

Before David could reply, he heard a rumbling. Maradi heard it too. It was low and distant, like a continuous peal of thunder several miles away. It rapidly grew louder, going from faint to ominous. Now it had a distinctive droning, whirring undertone. Maradi got up and went to the cave entrance to peer out. He muttered something to the two men outside.

David got up too, carefully, stealthily. Keeping an eye on Maradi, he began backing towards the inner chamber.

He knew what the sound was, what was making it.

RAF Eagles.

Two of them, he reckoned. Coming in low. Hedge-jumping. Under the radar.

There could be only one reason for that.

The noise had risen to near deafening now. Maradi turned to speak to David. He saw him ducking through the doorway in the inner chamber. A look of understanding dawned on his face. He began to shout out a warning to his men.

Then the jets roared by, skimming the valley's rim.

Then there was light. Milky jade-green brilliance. Blinding. Filling the world. And a detonation that punched the eardrums like knitting needles.

The cave convulsed. David was flung against the rear wall by a pressure wave. He fetched up sprawled across the corpses of his fellow paratroopers.

For a time, he couldn't move. Think. Feel.

He staggered to his feet. The air was dense with dust. The inner chamber was more or less intact, but the cave's outer wall had been reduced to rubble. A ragged aperture remained, large enough to clamber through. David made for it. On the way he stumbled across something on the floor. Captain Maradi. The Nephthysian was lying on his back. His clothing was charred and tattered. Most of the skin had been burned off him.

He stirred.