Costas wiped his visor, streaking it with brown, and stared speechless at Jack.
‘Actually, cesspits were quite hygienic,’ Jack said. ‘Each dwelling usually had one. It was only when they flooded that raw sewage was a problem, and then after people started using sewers that weren’t up to the job.’
‘Is that supposed to be reassuring?’ Costas sounded close to tears. ‘Come diving with Jack Howard. No latrine too deep.’ He tried to struggle upwards, and suddenly disappeared out of sight, then bobbed up again. ‘I thought so,’ he said. ‘There’s water flowing below us. This shaft has broken through into an underground stream.’
‘The tributary of the Walbrook stream, where they found the skulls,’ Jack said. ‘Maybe we’ve got a chance after all. If we can get into it and find another opening upwards, we might be able to get beyond that rubble obstruction to the edge of the Roman amphitheatre.’
‘Or we might join the city of the dead down here. Permanently.’
‘Always a possibility.’
‘Okay.’ Costas pulled out his waterproof GPS computer unit, and called up a 3D topographical outline he had programmed into it while they were waiting for the equipment to arrive in the church. ‘The flow of the stream is easterly, towards the Walbrook, which then flows south into the Thames. The outer edge of the amphitheatre is only five metres to the north of us. If we somehow get beyond that point, then we may as well turn back. We’ll be into the area that was dug up in the recent excavations.’
‘I’ll be right behind you,’ Jack said.
‘See you on the other side.’ Costas dropped below the water out of view. For a few moments there was a commotion as his feet broke the surface, then it settled down and the pool became a glistening sheen of darkness. Jack squatted in the water up to his chest, and listened to Costas’ breathing through the intercom. He thought for a moment of his own secret fear, the claustrophobia he fought so hard to control, and realized that his mind sensed a lifeline to this place, an exit route through the ancient crypt and the burial chamber to the church above. What lay beyond this pool was that crucial extra step beyond the escape route that could unnerve him, and he took a few deep breaths as he stared at the limpid surface. He felt vibrations, a slight tremor through his body, and watched the surface of the water shimmer. He guessed it was an underground train, passing through a tunnel somewhere far below. The sensation drew him back to the reality of the twenty-first century, and in his mind’s eye all of the tumultuous events of the past, the dark rituals of prehistory, the blood of the Roman amphitheatre, the Great Fire of 1666, the 1940 Blitz, all seemed to speed past him like a fast-motion film, leaving their imprint blasted into the cloying sediment around him.
He shut his eyes, then opened them again. He pressed the digital readout display inside his visor, scanning the figures that showed the remaining oxygen in his rebreather, the carbon dioxide toxicity levels. It was a reality check, and it never failed him. He heaved himself up, and realized he had nearly become stuck fast in more than a metre of mud at the bottom of the pool. After extracting himself he floated face down on the surface with his visor underwater, staring into swirling darkness with the dim patch of light from Costas’ headlamp directly below him. Jack arched down, bleeding air from his buoyancy compensator, and sank into blackness. About two metres down he could sense the flow of the underground stream, and he saw a tumult of clearer water where the silt was being swept away. The visibility was still only a matter of inches, but it was better than the black soup at the surface of the pit.
‘There’s an obstruction.’ Costas’ voice came over the intercom. ‘I’m nearly around it.’
Jack could sense Costas’ feet directly in front of him, churning the water as he heaved himself round a bend in the tunnel. Jack stayed back to avoid being kicked, and then as the turbulence subsided he let himself slowly fall forward, his hands splayed out to feel for any obstacle. After about two metres he felt something smooth, metallic, and then his shoulders came to rest on Costas’ legs. He felt a wriggling, then no movement at all, then a dull metallic thumping, then everything was still except the sound of their breathing.
‘It’s a Series 17 fuse. Good.’
‘What is?’ Jack exclaimed. ‘What’s good?’
‘This is.’ There was a clanging noise, then a curse.
‘What? I can’t see anything.’
‘This bomb.’
Jack’s heart sank. ‘What bomb?’
‘German SC250, general-purpose bomb. Carried by the Stuka, Junkers 88, Heinkel 111. They dropped thousands of them over here during the Blitz. Should be pretty routine.’
‘What do you mean, routine?
‘I mean, they weren’t delayed-action fuses, so they’re pretty routine.’
Jack had another sinking feeling. He thought of the tremor again, the vibration of the train. Suddenly this place seemed less solid, less stable, ready for history to have another go. ‘Don’t tell me what you’re about to do.’
‘Its okay, I’ve done it already. Done as much as I can.’ Costas’ legs shifted forward, and Jack dropped another metre in the water. ‘The forward fuse pocket was right in front of my nose, and I happened to have just the right socket in my e-suit equipment pouch. The after-pocket’s the problem. I can feel it, but it’s all rusted over. It’s not my style, but we might just have to leave it.’
‘Yes, we might,’ Jack said quietly. ‘How dangerous is it?’
‘The usual fill for an SC250 bomb was only 280 pounds of Amatol and TNT, sixty-forty mix.’
‘Only?’ Jack said incredulously.
‘Well, enough for us to be toast, of course, but the financial hub of the world would probably remain intact.’
‘I think there’s probably been enough human sacrifice at this spot,’ Jack said. ‘How stable is it?’
‘The problem’s that corroded rear pocket fuse,’ Costas murmured. ‘It’s been happily dormant for almost seventy years, but with our arrival, who knows.’
‘You mean after you tampered with it, who knows.’ The silt had settled slightly, and Jack could see the bomb casing about three inches from his face. It was corroded, deeply pitted, with no visible markings, and looked about as menacing as Jack could imagine. He was making the usual mental calculations, and this time the odds were not looking good. He sensed Costas shift forward and upward, beyond the bomb. ‘I think it might be time to leave now.’
‘Oh no.’
‘What do you mean, no? This thing’s still live. We need to get out.’
‘No. I don’t mean that. I mean this, in front of me.’ Costas was almost whimpering. ‘It’s another nightmare. It’s just getting worse.’
‘Okay. I’m coming.’ Jack eased himself deeper, with the corroded bomb casing just in front of his face, until he saw where it curved down to the nose cone and suspension lug. He turned over on his back and put his hand on the lug to keep his body from jolting against the casing, which seemed to be suspended perilously in mid-water. He slowly pulled himself up until he felt the casing between his legs, and then below his e-suit boots. At the point where he imagined the base plate and tail fins should be, he suddenly broke surface, his face inches from a slimy mud wall. He had been fine in the silt, underwater, with his face pressed close to the bomb casing, but now he suddenly felt unnerved, as if those extra few inches of visibility were just enough to give him a sense of how confined the space was. He knew he had to fight hard now, concentrate entirely on what they were doing. He rolled over slowly, careful not to budge the bomb casing, until he was beside Costas and facing in the same direction. He could feel the compacted gravel of the ancient stream bed below his feet, showing they had come under the archaeological layers. He angled his headlamp upwards, and gasped with astonishment. They were inside some kind of structure, a chamber, with unworked tree trunks lining the roof about two metres above them. He saw massive beams of blackened oak, with bracing timbers around the walls. He looked down, following Costas’ gaze.