‘That didn’t work too well. Was hoping the whole thing would come down, but whoever built these pipes did a good job.’ he said. ‘Good job to them, bad luck to us. That won’t hold ’em long. What’s going on there?’

They turned with him towards the right. The third Outlier, the one called Kieran, seemed to be having some trouble with his tunnel. He was firing away, beams ricocheting all over the inside, but the pipe held firm.

‘Oi, there! What do you think you’re doing, boy?’ roared Ollie, racing towards him. They all followed him as he sped away, skidding to a stop next to the man, his shoes scuffing up the loose earth on the floor.

‘Not the centre! Shoot at the sides! The sides! Ah! Just move!’

Shoving the man aside, he took a few paces into the tunnel and lifted his gun, pointing at the place where the pipe began to curve downwards. ‘Always the sides, lad! It’s—eh, what do we have here!’

They could hear the delight in his voice, carrying back to them. ‘Told them you’d—Ah!’ He broke off suddenly, biting off a curse. A moment later his voice echoed down the corridor again, but the cheerfulness was gone.

‘Wait, let me help you. Hold on. Steady now.’

Marcus stepped out of the shadows of the pipe, Ollie beside him. Together they supported a third man, deathly pale, shivering and sweating profusely, who was making short, gasping sounds, between a sob and a hiccup. He had an arm around each helper’s neck. One leg trailed lifelessly on the ground, and where the other leg should have been—it was a sight Albert knew he would never forget; it would haunt him forever—there was nothing. Shards of bone and errant strips of raw flesh hung out from a burned trouser leg that had been blown away halfway up his thigh. As he moved, drops of blood dripped from a makeshift tourniquet tied around his wound, marking a steady, macabre path behind him.

Next to Albert, Colby’s eyes widened. ‘Zain!’

Everyone rushed towards the man who was being gently lowered on to the cavern floor. ‘Zain! What happened?’

The man coughed and turned on his side, sobs wracking his thin frame. He looked up at Colby and tried to speak, but could only gasp. Blood dribbled from his lips. He had bitten his tongue. He coughed again, and spoke in a low, husky whisper.

‘Bots.’ He turned over on his side again, coughing some more. Then his eyes rolled up and his head lolled back. He had fainted.

‘I found him in the tunnels,’ said Marcus. ‘He was trying to drag himself here.

Albert looked at the man—no, not man, boy—he couldn’t have been more than seventeen or eighteen. Light stubble ran across his white face, the kind that had never seen a razor. His lips were rimmed red now.