Sherlock found the journey strange and disturbing. Water sloshed in the bottom of the boat and there were things floating in the river that he tried hard not to look at: human waste, dead rats and lengths of sodden wood covered in weeds. The smell was so appalling that he had to breathe through his mouth, and even then he was sure he could taste the smell as it coated his tongue and the back of his throat. It made him gag. At one point another boat emerged from the murk and pa.s.sed close to them. Someone shouted a curse, and their boatman replied with a gesture that Sherlock had never seen before but could translate pretty well.

It took twenty minutes or so to make the journey to Rotherhithe, and they disembarked on a set of steps that were almost indistinguishable from the ones that they had started from. Crowe led the way up to the top.

A narrow alley cobbled with rough stones ran along the riverbank, curving away to either side. Crowe led Matty and Sherlock along it, past the towering edifices of warehouses and brick walls, following the edge of the malodorous Thames and keeping to the shadows wherever possible. After ten minutes or so he stopped. Opposite them was one of the taverns that could be found everywhere across the metropolis. The jangly music of a badly tuned upright piano emerged through the doorways and the windows, along with a jumble of voices singing different words to the same tune. Several women stood in a doorway and eyed Amyus Crowe with interest before turning away when they saw Sherlock and Matty.

'I believe the warehouse is just around the corner,' Crowe murmured. His attention was focused all around them, looking for threats. 'I suggest we check out the lay of the land and settle down for a while,'

'What if we're seen?' Sherlock asked.

'I used to be a hunter, back in Albuquerque,' Crowe said. 'I tracked some of the most dangerous beasts around. There's things you can do to minimize the chances of gettin' discovered. Don't make eye contact, for a start, cos all animals spot eyes straight away. Look at things out of the corner of your eye it's more sensitive than lookin' straight, although you don't make out colours too well. Don't move if you can help it, cos the eye is set up to spot movement, not things that are still. Wear dull clothin' that doesn't have any colours that you wouldn't see in nature grey for stone, green for moss, brown for earth. And don't wear any metal, cos metal ain't found in nature in any great quant.i.ties. Follow those rules and you can stand against a brick wall and folk'll just let their eyes move over you an' on till they find somethin' more interestin'.'

'It sounds like magic,' Sherlock said, unconvinced.

'Most stuff does till you know how it's done.' He glanced critically at the two boys. 'Those cuts on your face will help you blend in, Sherlock, but you're both a mite too neat for this neighbourhood. Need to dirty you up a bit.' He looked around. 'OK, I need you to roll around on the cobbles for a while. Get some dust into your clothes.'

'Won't that be suspicious?' Sherlock asked.

'Not if you got a reason for it,' Crowe explained. 'Matty, shove young Sherlock here in the chest.'

'What?' Matty responded.

'Just do it. An' Sherlock, you punch him on the shoulder right back.'

The light of understanding dawned in Sherlock's mind. 'And we end up sc.r.a.pping in the dirt, which helps our clothes to blend in and and establishes us as part of the area. If we weren't local, we wouldn't be fighting in the road.' establishes us as part of the area. If we weren't local, we wouldn't be fighting in the road.'

'Exactly,' Crowe said approvingly.

Sherlock was about to ask how long they ought to fight for when Matty shoved him hard in the chest. 'I told told you!' he shouted. you!' he shouted.

Sherlock suppressed the sudden urge to punch Matty in the jaw, and instead hit him on the shoulder. 'Don't you dare,' he yelled, feeling slightly embarra.s.sed.

Matty launched himself at Sherlock, bringing him to the ground. Within moments the two of them were rolling around, clouds of dust rising around them. Sherlock got a grip on Matty's arm, but Matty's fingers closed in Sherlock's hair and pulled his head back.

Sherlock was on the verge of forgetting that it was a pretend fight when Amyus Crowe's huge hands closed on his and Matty's shoulders and hoicked them upright. 'All right you two, break it up,' he said, using his 'English' voice again, but gruffer this time.

The two boys stood facing each other, trying to suppress smiles despite the danger of their situation. Sherlock glanced down at himself. His jacket was torn at the sleeve, and everything was covered in dust and horsehair and stuff that he didn't even want to think about.

'Don't worry,' Crowe said. 'It'll wash off. And if it doesn't, we'll just buy more clothes. Possessions can always be replaced. A good hunter knows that anything material can be sacrificed in pursuit of the prey.'

'What kind of animals did you hunt?' Matty asked.

'I didn't say they were animals,' Crowe murmured.

Before either of the boys could ask him to clarify his statement, he walked off. They followed, exchanging uneasy glances.

Crowe stopped at a corner and glanced round it. 'Warehouse is across there,' he said quietly. 'Sherlock, you stay here. Hunker down on the ground an' play with somethin' some stones if you can find 'em. Remember don't make eye contact, but watch what's goin' on out of the corner of your eye. Matty, you come with me. You can cover the back, an' I'll move back and forth between the two of you.'

'What are we looking for?' Sherlock asked.

'Stuff that's out of the ordinary. Somethin' that might tell us what's goin' on here.'

Crowe and Matty walked off, Crowe's hand on Matty's shoulder, and Sherlock followed instructions, settling down on his haunches and pulling one of the cobbles from the mud. He rolled it back and forth. It was a boring game, but it was enough to make him look like part of the scenery, and he found he was still able to see what was going on around him out of the corner of his eye while ostensibly playing his game.

The warehouse was a brick building with a front made up almost entirely of a large pair of wooden doors, hinged so that they opened outward on to the street. There was nothing obviously suspicious about it, and Sherlock wondered whether they were actually watching the right place, or just a randomly chosen building.

Amyus Crowe wandered back after what seemed like hours, but was probably closer to half an hour. Although he was wearing the same clothes as before, and he hadn't dirtied them as noticeably as Sherlock and Matty, he looked dishevelled. His jacket was b.u.t.toned up wrongly, giving him a lopsided appearance, and his shirt was hanging out of his trousers. He was weaving slightly, and staring at the ground directly in front of his feet. He stopped near Sherlock and slumped against the wall.

'Everythin' OK?' he murmured.

'Nothing's happened,' Sherlock replied, equally quietly.

'You all right?'

'I'm bored.'

Crowe chuckled. 'Welcome to the hunt. Long stretches of boredom punctuated by moments of exhilaration and terror.' He paused, then went on: 'I think I might wander into that there tavern for a while, see what's bein' said.'

'Fine. Couldn't send me out a gla.s.s of water, could you?'

'Son, you're prob'ly better off drinkin' out of the Thames than the water from any tavern around here. If you're hungry or thirsty just register the fact an' then push it to one side. Don't dwell on it. A human being can go three, four days without water. Just keep tellin' yourself that.'

'Easy for you to say.'

Crowe laughed.

'Can I ask you something?' Sherlock said, wanting to keep Crowe there for a few moments more.

'Sure.'

'What are you doing in England? What is is that "business" you mentioned earlier?' that "business" you mentioned earlier?'

Crowe smiled without humour, and glanced away, not meeting Sherlock's gaze. 'Not to be a tutor, that's for sure,' he said softly, 'although that's becomin' an interestin' pastime. No, I was retained by . . . well, let's say the American government to make it easy, to seek out men who'd committed crimes, atrocities, the most terrible things durin' the recent Civil War an' escaped the country before the hand of justice could come down on their shoulder. That's how I came to know your brother he signed the agreement that allows me to be here. An' that's why I've been developin' a network of useful people, especially in docks and ports. So when you told me that the Baron was accelerating his plan, whatever that may be, I just sent out the word to look for his carts. An' I got to say, I was surprised that my people found them so easily.' He looked back at Sherlock. 'Satisfied?'

Sherlock nodded.

'Not many people I've told that to,' Crowe added. 'Grateful if you'd keep it to yourself.' He moved away before Sherlock could say anything more.

Sherlock continued playing his game, rolling the cobble back and forth, as the minutes slid away, one after the other. He kept watch on the warehouse doors, but they were firmly closed and nothing was stirring. He was beginning to think that they were all on a wild goose chase.

A sudden escalation of noise from behind him almost made him turn and look, but he stopped himself just in time. He let the cobblestone run a little further, turning to retrieve it and letting his eyes drift upward to take in the tavern. One of the doors was open and a group of men were emerging, obviously the worse for drink. They bantered for a moment, then turned and walked towards him. He concentrated on his stone, listening to whether they were saying anything about the warehouse, or the beehives, or Baron Maupertuis, or anything related to the mystery.

'When're we hauling out?' one of them said.

'First light tomorrow morning,' another replied. There was something familiar about the voice, but Sherlock couldn't quite place it.

'Who's got the roster?' a third voice asked.

'It's in my head,' the second man replied. 'You head off to Ripon, Snagger goes to Colchester, the lad Nicholson here gets an easy ride to Woolwich an' I get to go back to Aldershot.'

'Can't I go to Ascot instead?' asked a Northern-accented voice presumably the lad Nicholson.

'You go where you're told, sunshine,' the second man responded. As he was talking, he pa.s.sed close to Sherlock. His foot caught the cobblestone, kicking it across the alley. Unwittingly, Sherlock glanced up and met the man's gaze.

It was Denny, the man who Sherlock had followed back to the warehouse in Farnham, the man who had been there when his friend Clem jumped on the narrow-boat to attack Sherlock and Matty. The man who worked for Baron Maupertuis.

So much for being invisible. Denny's face instantly flushed with anger.

Sherlock rolled away as hands reached for him. He sprang to his feet and sprinted off down the alley. He wanted to run towards the tavern where Amyus Crowe was, but the men were between him and the tavern door. Instead he found himself running further and further away from Crowe, from Matty and from anything he knew.

Footsteps thudded behind him, echoing off the walls of the buildings as he ran past them. His breath rasped in his throat and his heart pounded like a living thing trapped inside his ribcage and fighting to get out. Twice he felt fingers touch the back of his neck and scrabble for a grip on his collar, and twice he had to tear himself loose with a frantic burst of energy. His pursuers were growling beneath their breath as they ran, but apart from that, the thud of their boots and the sound of his heart, the chase was conducted in complete silence.

He could see as he got halfway down that the alley finished in a brick wall. Sherlock's eyes widened. He was trapped! He turned, desperately trying to work out if he had enough time to run back and find another way, but the men were closing in on him. There were five of them, he noted in a kind of terrified calm, and they were all holding knives or heavy sticks. He wasn't going to get out of this alive.

A voice suddenly sounded very clearly in his head, and he couldn't tell whether it was his brother's voice, or Amyus Crowe's voice or his own, but it said: 'Alleys and roads lead from one place to another. An alley that ends in a brick wall is illogical. It has no purpose, and therefore should never have been built.'

Sherlock swung back and let his gaze scan the brickwork of the alley. No doors, no windows, nothing but a patch of shadow in one corner where the lackl.u.s.tre sunlight could not penetrate.

And if there was a way out, that was where it would be.

He ran into the shadows. If there had been nothing there then he would have run straight into the brickwork, knocking himself out, but instead there was a slender gap. A means of escape.

The narrow walkway ran between two buildings. He raced along it, hearing shouts of frustration from behind him as the men tried to find the dark way out. Single file they stumbled into the walkway after him, the grunts of their breath echoing from the steep brick walls.

Zigzagging through the darkness, Sherlock stumbled out into a wide road lined with doors. He ran on, sensing boots. .h.i.tting cobbles behind him, and skidded left into another alley, gaining himself a few yards more. A dog sprang out of a gap in the wall as he pa.s.sed, but he was gone before its teeth closed on empty air. Instead, it turned on the men chasing him. Sherlock heard furious barking and the sound of cursing as the men tried to get away from it. He winced at the noise of a boot thudding into something soft. The dog whimpered and scrabbled away.

Scooting round another corner, he ran full tilt into a man and woman walking along the side of the Thames, sending the man sprawling and himself spinning backwards.

'You little beggar!' the man shouted, heaving himself back to his feet. 'I'll teach you what for!' He started pushing the sleeves of his jacket up, revealing muscle-swollen forearms covered with blue tattoos of anchors and mermaids.

'Don't touch him, Bill. He didn't mean it!' The woman clutched at her companion's arm. Her skin was white with badly applied make-up, her lips a crimson slash, her eyes shaded with black powder. The effect was to make her face look like a skull. 'He's only a kid.'

'I thought he was a thief,' the man growled again, but less aggressively this time.

'There's men after me,' Sherlock said through his heavy panting. 'I need help.'

'You know what they do to boys round here,' the woman said. 'I wouldn't wish that on my worst enemy. Bill, do something. Help the lad.'

'Get behind me,' Bill said. Sleeves pushed up, he was obviously itching for a fight not too concerned who it was with. Sherlock slipped behind the man's ma.s.sive bulk as his pursuers came around the corner.

'Stop right there,' Bill said, his voice low and full of the promise of violence. 'Let the kid be.'

'Not a chance,' said Denny, who was at the forefront of the five men. He brought his hand up, and he was holding a knife. Light trickled along the edge of the blade like a glowing liquid. 'He's ours.'

Bill reached out to take the knife, but Denny tossed it from his right hand to his left and punched it forward, into Bill's chest. The man fell to his knees, coughing blood, a disbelieving look on his face as if he couldn't accept that these moments, here in this alley, would be his last.

Denny smiled at Sherlock as Bill fell forward on to the cobbled surface of the road. 'With you,' he promised, 'it won't be so quick.'

CHAPTER THIRTEEN.

Sherlock's whole body seemed to freeze in horror and disbelief, then a white heat of rage pa.s.sed through him. Stepping forward, he punched his fist hard into Denny's groin. The thug folded up, choking. As he collapsed, Sherlock stepped back and kicked him in the jaw. Something cracked. The man screamed through a mouth that suddenly seemed to have locked in place, and was twisted to one side.

The woman Bill's companion screamed as well, a high, piercing shriek that cut the air like a knife.

The other four men looked at each other in disbelief, then moved forward and reached out their grimy hands for Sherlock. Every detail was etched into Sherlock's mind: the dirt beneath their nails, the hairs on the backs of their hands, the blood pooling on the ground, the shriek of the woman and the scream of Denny melding into one continuous whistle of pain. The world seemed to slow to a halt, freeze, and then shatter into pieces around him. He turned to the woman, his mouth dry. 'I'm so sorry,' he said.

Then he was running again. Two of the men followed, leaving Denny behind, collapsed on the cobbles beside Bill. The woman just stood there, looking down at them both, her scream gradually fading into choking sobs.

Turning a corner, Sherlock saw a ma.s.sive domed building ahead of him. It looked entirely out of place in the middle of a cleared area of ground which had been planted with bushes and trees. Several roads wide roads, not alleys led away from it, and there was a constant bustle of people and horses swarming around outside. Beyond it Sherlock could see a stone wall and, further away, the churning grey surface of the Thames.

Sherlock ran towards it. Where there were people, there was likely to be safety.

Sprinting, he swerved past well-dressed men and women and ducked beneath the shafts of a carriage, heading all the time for the building. As it grew closer he could see that it was decorated with statues and tiled mosaics. A large entrance loomed up ahead of him, and he diverted his course slightly to head straight for it. Behind him, curses and shouts indicated that his pursuers hadn't given up.

The entrance led into a circular hall, lit by the sun shining through a myriad of coloured gla.s.s windows in the domed ceiling. The light gave a clownish, harlequin air to the place. In the centre of the building was a hole ringed by a balcony. People were lined up along the balcony, gazing down at something. Over to one side, a wide stairway spiralled round the edge of the pit, into the depths of the earth.

Sherlock dashed across, pushing through the throng of people, and reached the top of the stairway. Turning, he glimpsed the two men shoving their way through the crowd. One of them was a bald man with deformed ears and nose, leading that small part of Sherlock's brain that wasn't frantically trying to work out ways of escape to think that he might have been a boxer. The other was painfully thin, with sharp cheekbones and a pointed chin. They were obviously set on catching him, no matter what. Perhaps before he had broken Denny's jaw they might have given up, but they were driven by a purpose now. One of them had been humiliated, and so Sherlock would have to pay.

He turned, and started down the staircase.

The stairs spiralled around the sides of a tremendous shaft, levelling out every now and then on a balcony but then continuing down into the abyss. A smell rose up out of the shaft: a stench that combined damp, rot and mould into a single foetid odour that made his nose tingle and his eyes water. Sherlock's steps fell into a repet.i.tive routine as he pounded round the sides of the cylindrical shaft. He had no idea what was at the bottom, but a single glance across the shaft told him what would await him at the top. Two of Baron Maupertuis's men were racing down the steps towards him.

He sped up. Whatever was at the bottom of the shaft couldn't be as bad as the certain and probably slow death that was chasing him.

He seemed to have spent much of the past few days running or fighting, and even as his feet clattered against the stone steps and his hand burned as it sc.r.a.ped against the banister there was a part of his mind that wondered frantically what exactly Baron Maupertuis thought he knew that was so important he had to die for it. What exactly was the Baron planning to do, and why was Sherlock an obstacle to his plans?

He was at the bottom before he realized, feet stumbling on the level surface. He was in a gas-lit hall. Two arched tunnels led away from the hall, both heading in the same direction. The arches were fully four or five times the height of a grown man, and made of brick, but the brickwork was wet everywhere he looked. Judging by the direction taken by the tunnels, he knew why. They went straight out under the Thames, and presumably ended at a similar shaft on the north side.

If he could make it to the other side, he might just escape with his life.

He stumbled on into the left-hand tunnel. There were people ambling along as if walking beneath the surface of a river was nothing special. There were even horses down there, being led calmly along. They obviously had no idea about the uncountable tons of water just a few feet above their head, kept at bay by crumbling brickwork and plaster.

There were times when being too logical was a curse. This was one of those times. Sherlock knew the kind of pressure that was being exerted on the tunnel walls. One slight crack and the water would pour in, drowning them all.

But he kept on running. He had no choice.

Or did he? As he hurried on, he noticed that the two tunnels ran in parallel, and were linked by smaller side tunnels every ten yards or so. In each of the side tunnels enterprising Londoners had set up stalls selling food, drink, clothes and all kinds of bric-a-brac. If he could just worm his way through one of the side tunnels, he could go back down the other main tunnel to the shaft, return to the warehouse and find Amyus Crowe.

He veered right, towards the side of the main bore, and nipped into the first side tunnel he came to. A man turned towards him, illuminated by an oil lamp that hung from a nail on his wooden stall. His skin was grey-white and moist, like something that had lived underground for too long. He was wrapped in an old blanket that had become stiff with dirt over time, like some bizarre armour. His eyes seemed to be all black pupil, and he peered at Sherlock for a moment.

'You want a clock?' he said hopefully. 'Good timepiece. Always right. Always correct. Grandfather clock, grandmother clock whatever you want, I got.'

'No thanks,' Sherlock said, pushing past the stall. It occurred to him that time was meaningless beneath the Thames. No sun, no moon, no day and night. Time just pa.s.sed. Why would you need a clock?