CHAPTER ONE

      ‘There ain’t many things in life I’m afraid of, sir … ’

      ‘But … ?’ Sergeant Harry Pilgrim glared up at the constable from halfway down the sewer ladder.

      He hopped from one foot to the other, peering down at his superior. ‘Rats is one of them.’

      ‘Rats?’

      ‘Just so, sir. Fearful scratchy, louse-ridden creatures, sir, and I could no more go down that hole with you than walk on water, sir, even if you paid me a hundred guineas.’

      Pilgrim looked at the constable. They both knew he earned just twenty shillings a week.

      ‘I don’t have time for this, Wainwright. Pass me the tinder box.’

      ‘Here it is, sir.’ The constable’s face slackened with relief.

      Pilgrim took the box and tested the wheel. It fired readily; spinning sparks into the darkness as he descended the ladder. The rungs were surprisingly dry – it hadn’t rained for more than a fortnight – but even so, Pilgrim landed at the bottom with a splash. He didn’t look down to see what he had landed in, but up instead, to Wainwright’s face, haloed by the night sky like a lugubrious saint.

      ‘If I’m not back in five minutes go to the barracks.’ Pilgrim’s voice echoed off the arched brickwork. ‘Tell Constable Williamson where I am, and get him to wake some of the men to follow me.’

      ‘Will do, sir … and sorry, sir … about the rats.’

      Pilgrim sparked the tinderbox again, and lit the wick of the lamp. He raised it up. He was in one of the new parts of the sewer system. The roof was easily high enough for him to stand, but the bricks were already crumbling, and daubed with rust-coloured streaks. It wasn’t rust, of course.

      Pilgrim grimaced. He was glad that smallpox had robbed him of his sense of smell. He knew he had to hurry. The man he was pursuing was at least five minutes ahead of him now. He pressed on into the sewer; a straight tunnel with no turns or visible exits.

      ‘… seventy-four … seventy-five …’ He counted the paces, until he reached a point where the tunnel split into two. He hesitated. His quarry could have gone down either of them. But which one? He lifted the lamp higher, and listened. Nothing. Except the scratch of claws on brickwork. He could make out the huddle of rats on the copings beyond the range of his lamp. It was just as well Wainwright hadn’t wanted to join him. On the other hand, if he had, they would at least have been able to explore both routes. Frustration welled. Pilgrim had come so far, but now found himself torn between choosing one of the tunnels at random and turning back.

      Then he heard it: the rasp of metal on metal, coming from the left hand branch. He took off his scarf, hung it on a nail that was protruding from the wall of the left hand tunnel, then galvanized into action, wading through the water as quickly as he could. It was impossible not to splash, but he hoped that the man he was chasing would be too absorbed in his own progress to hear the pursuit. Pilgrim ran on through the greasy water. Something caught at his foot. He lurched and stumbled, pitching forwards, then floundered a moment, grabbing for something, anything, that might help to keep his face out of the filth. His fingers closed on something substantial, and he used it to push up onto his feet. Releasing it, he recoiled at the sight of an eye staring up at him. A dead dog.

      He made an effort to steady the pounding of his heart. At least he hadn’t dropped the lamp. He listened. Nothing. All his senses told him he was alone in the tunnel.

      ‘Bollocks.’

      He lifted the lamp. More brick, more slime, more black water, stretching away into the darkness. But there, on the boundary of the glow cast by the lamp, he saw something else: rungs set into the wall. He waded towards them and peered up at a manhole cover. If his suspect was no longer in the tunnel, he had to have