Porter gripped his M16 tight to his chest. Lights were flashing on the Puma, and the roar of the engine as the hatch opened was deafening. ‘Go,’ shouted Steve. ‘Bloody go.’

Four sets of ropes were tossed out of the side of the Puma. With his legs kicking across the metal, Porter pushed himself out. Steve went first, then Porter, then Mike and Keith. Collinson was hanging back, Porter noted. A cloud of dust was shooting straight up into the sky as the chopper hovered a foot above the building, creating a brilliant, illuminated light that made it impossible to see anything. Porter gripped hold of the rope, and slipped down it, then threw himself down hard onto the roof of the building.

‘Move up,’ shouted Steve, his voice raw and hoarse.

They had practised this manoeuvre a hundred times back at the killing house. Go in hard and fast. Maximum speed and maximum aggression. The tactics were settled. But it was always different in real life. Back at base, the opposition was just pretending to kill you.

They had landed on a flat roof, with a single doorway leading down inside the two-storey building. Steve and Mike had already shot the door open, and the two men were fearlessly leading the way. Porter ran after them, his ears cocked for the first round of gunfire that would inevitably greet them, and weapon cocked tight to his chest, his finger poised on the trigger, ready to fire. Collinson was lagging a couple of yards behind the pace.

‘Take out, take out,’ Steve shouted.

Porter dropped to his knees as soon as he hit the first-floor landing. He could see the man clearly enough: a solitary figure, swathed in black robes, with an AK-47 tucked into his chest and dark glasses covering his eyes. Pressing the trigger on his M16, Porter loosed off a barrage of fire. At his side, Mike and Keith had done the same. A lethal hailstorm of bullets was biting chunks out of the bricks and mortar. Enough of it lodged into the chest of their sole opponent to send him crashing back against the wall, blood spurting from a dozen different wounds, and a pitiful moan erupted from his lips as he clung miserably on to the last few seconds of his life.

Steve kicked the body out of the way, affording it the merest glance to make sure there was no more breath left in it. The house was a simple, flat-fronted concrete structure, and it was only the intelligence reports that told them it was the front for an underground complex of bunkers. Another man was already running into view. A burst from their assault rifles quickly finished him off. Another bullet-ripped corpse lay in front of them. Porter could feel the excitement rising within him, making him stronger as each second passed.

With a rapid burst of fire, Keith and Mike had kicked their way through to the ground floor of the building. There was a simple square room, measuring twenty feet by twenty-five, with a couple of motorbikes stored in one corner. It smelt of soldering irons and diesel oil. To the back, there was a staircase, leading downwards. A pale light was snaking its way up to the surface. Porter paused for a moment. There was a brief, eerie silence as the guns stopped their murderous fire. He looked left, then right. Suddenly there was cry, followed by a burst of fire. Porter could feel a chunk of the wall right next to him being cut open by bullets. He dropped to his knees and squeezed the trigger on the M16. He didn’t even know what he was firing at until he saw his assailant keel over.