I set the oil lamp on the stone just below me and turned to pull the trap shut above us. The steps were so narrow my hips scraped against the wall as I shuffled about. No wonder Fitzy didnt have much call for the 'hidey hole. If hed ever managed to cram his corporation down here then I reckoned he had a future as a contortionist.

I called down. 'Youll have to bend your head, Della, the ceilings low.

Her coughing echoed from the walls as she reached the bottom and I heard the material of her coat rustle as she turned the tight corner. I took up the lamp and followed.

Della leaned awkwardly against the stone, her head bowed forward under the low bricks arching above. The damp muslin hung like a scarf at her collar. She brushed her lips over the top of Robbies head and he blinked at the light as I paused at the curved entrance to the little chamber. Hed stopped crying now.

I loosened the muslin and breathed in. The air was foul down here too, but it was the foulness of a street sewer, not smoke. That was something at least. It was cold, too. I could see my breath, not smoke, fug up in front of me. I was glad of Nanny Pecks shawl.

'Budge up then, Della. Theres just enough space. If we can sit it out down here then maybe- We both flinched as a thundering crash rolled overhead. The ominous sound echoed from the stones. Brick dust pattered from the arches, falling across my eyes, my nose. I wiped it away, tasting the earthy metallic powder on my lips.

Then maybe what, I wondered? Even if we didnt suffocate, would anyone find us buried down here?

I pushed the thought away.

'Sit, Della. Its easier than leaning. I dipped my head to go through the arch and I shrugged Nanny Pecks shawl to keep it over my shoulders.

'We cant sit, Kitty theres water everywhere.

I heard a soft splash as I stepped down. There was a rush of wetness in my boot. I held the lamp forward. Della was right. A shimmering black pool covered the four square flagstones I was expecting to see.

'But thats never been here before. I dont understand . . .

Of course! It was rain Lucca had said as much when I was entertaining Sam. The cellars at The Gaudy always took on water when the drains couldnt cope. Mostly it didnt matter the bottle stacks were sound but the barrels, specially the older ones, could soak through corrupting the liquor inside.

I should have listened to him and got Fitzy on it, like I said I would. Not that it mattered now.

'What next? Della stared at me. Her pale eyes were like pebbles in the lamplight. They were dead, like every last bit of hope had been rubbed away. The light carved out great dark hollows beneath her cheeks. Her strong-boned face didnt have the usual curves or cushions of a woman. Of an instant I could see how Id fallen for the lie and, for some reason, that made me feel better.

I raised the lamp and the flame jittered in the glass.

'Well wait it out. The water wont rise above here. I made a chopping motion with my free hand below my knees. 'It never does.

Another rumbling sound came from above. The wall at my back juddered and more dust fell over my head and shoulders. I coughed as it caught at the back of my throat.

'And then what, Kitty? Even if we live, no one will find us down here. They wont think to look for us under the rubble. No one even knows were here. Della nodded at the lamp. 'When that goes out it will be dark as a tomb. Its hopeless. One way or another were dead.

My heart began to rattle about in my chest like it was trying to find a way out. Thing is, I didnt much care for small spaces. When I was around five or six, Joey had locked me in a tea chest when we were playing in the old goods yard up Shadwell. Hed gone off and Id cried and screamed and beat on the sides thinking he wouldnt come back. I scraped so hard on the lid that my fingers bled. It seemed like a day, but half an hour later when he finally slipped the wooden peg to free me Id disgraced myself.

I didnt mind heights, but there was something about crouching here while a hundred tons of bricks and rubble collapsed overhead that put me in mind of that tea chest.

Wedged up against her, I felt Della tremble. Then she began to cry, not loudly which, curiously, made it worse. No, these were dry, heaving sobs she tried to swallow down. Robbie stared up at his mothers twisted face and then he began to bawl. His thin reedy wails bounced off the stones so they cut straight through you.

Christ! That was all I needed. I couldnt stay here.

I gathered up my skirts, gripped the lamp, ducked my head through the arch and went up the first two steps. I held up the light and saw tendrils of black smoke creeping around the corners of the trap. The air smelt of gas and burning wood.

My heart was beating so hard now it was knocking against my ribs. I could hardly breathe. I tried to gulp down some air and heard the ragged sound in my throat as my chest tightened up to block the way.

Della was right. It was hopeless. I rested my head against the cool damp wall for a moment.

Think, girl, think. My head was spinning. I breathed deep again, trying to force the air down into my lungs.

Think.

I turned back and squeezed through the arch again, the water reached above my ankles now. It was rising faster than I expected, but where was it coming from? I scraped my eyes across the walls. The safe was lodged halfway up in the bricks at the end of the chamber. The wall to the left seemed to be blocks of stone. Over to the right, behind Della and Robbie, there was more stone and a band of bricks curving up to fan across the low ceiling.

'Della, shift forward.

When she didnt move I shouted at her. She stopped sobbing and stared at me blankly, her hand softly caressing the furred brown ball of Robbies head.

'Why? Whats the point?

'Because the waters coming in from somewhere, and I want to see it. Now, move. I softened my tone. 'Please.

She shrugged and shuffled away from the wall. We danced around each other until I could take a better look. At the bottom, just above the water line, there were a couple of missing bricks, and a thin trickle of water spilled through the hole. I bent lower and blocked my nose at the evil smell. That was where the sewer stink was coming from. I pushed my hand into the gap, expecting to make contact with more brick. When it didnt I forced it in further. It went straight through to the elbow and I groped into nothingness beyond.

I pulled my arm back. As my hand came free it dislodged another of the bricks, dragging it partially from the wall so it jagged out at an angle. I ran my fingers over the wall. The mortar at this level was soft and crumbling to the touch. Years of water had softened the bonds.

I straightened up as far as I could.

'Della, can you take the lamp for a moment and still keep hold of Robbie?

She balanced him on one hip and reached for the lamp. She didnt say anything as I knelt in the water and scrabbled at the brickwork, gouging the mortar out from the bricks with clawed fingers.

First one, then two, then three, four bricks came loose. I pulled them free and piled them carelessly beside me. There was a hole the size of a mans head low down in the wall now.

'Pass me the lamp.

I held it to the gap and peered through. At first I couldnt make anything out, but as the flame flickered it cast light on what seemed to be an arched tunnel of a mans height filled with water. I glanced up. Della was leaning back against the wall with her eyes closed. Robbie freed an arm from his blanket wrapping and reached down to the light, his fat little fingers opening and closing on nothing.

'Theres a way out. If we can make a hole big enough we can get through. It must go somewhere. Well?

When Della didnt move I snapped at her. 'For Gods sake, and if not His, for Robbies, help me!

That did the trick. I didnt have Della Lennox down as a Bible type, but I knew enough now to realise that baby was her religion. She nodded sharp, folded herself over to lay Robbie on the step leading into the chamber and turned back to kneel beside me.

Gathering some of the discarded bricks together she took the oil lamp from me and balanced it on them above the level of the water.

'Here. I fumbled in my pocket and took out the shards of oyster shell Id found on The Gaudys floor. 'Use these to dig at the mortar. It comes out easily enough, but some bits are more solid than others. These are sharp and hard as stone.

We knelt there side by side, hacking at the wall with our fingers and the bits of shell.

Within five minutes wed trebled the size of the hole in the brickwork. At first Della worked slowly as if she couldnt believe it would make a difference, but as the gap widened and the bricks came free she took in the empty blackness beyond and she began to believe.

Once she began to believe she began to work.

'Thats enough. I sat back. 'We can get through now. Its easily big enough.

We glanced at Robbie on the step as another booming sound reverberated above, loosening dust from the ceiling and more bricks in the gap wed made. One of them fell back into the blackness beyond and we heard it splash into the water.

Della rubbed a hand across her face. Shed taken off her gloves to scrabble at the wall and her dark skin was criss-crossed with cuts where shed misjudged her frantic gouges with the shell.

'How deep is it?

'Ive no idea. The only thing I know is that its a way out. Ill go first.

Della caught my arm as I pulled up my sodden skirts and made to scramble through the gap. 'I . . . I cant swim, Kitty.

'Neither can I least Ive never tried. But theres not much else we can do, is there? Once Im through try to pass me the lamp, then Robbie, then you follow him. Is that clear?

She looked doubtfully at the hole.

'It cant be any worse than this, can it? We both ducked as something heavier than brick dust rattled from above. It came to me then, that for all her en travesti, or however she liked to dress it up, I was the one with what Lucca called coglionis.

I was about to say something of the sort, when I caught the expression on her dust-smeared face. She was staring over at Robbie, her face tight with a terrible aching determination that set the raw bones even sharper in her cheeks. She was gathering herself together for his sake.

I felt a whip smart of shame and buttoned it. Della must have gone through so much already to protect her kid, things I couldnt imagine. I took her wet hand in mine and squeezed it.

'Listen this is a way out. We have to try it. Ill go first.

I ruffled up my skirts, leaned forward and squeezed through the hole into the darkness. When I was halfway through I plunged my hand down into the water and my palm scraped against something solid. The water in the tunnel was less than a foot deep, but it wasnt clear. I was glad I couldnt see the things bobbing against my skin. Beneath my hand I could feel something like a mat of slime-coated hair floating up to knot itself between my fingers. The stench was something chronic.

I hauled myself through, flopped down into the muck and tried to block my nose as I splashed to my feet. I bent level with the glowing gap.

'Its not deep, Della. I can stand. Your turn now.

'Which way?

I held the lamp higher and tried not to notice that the flame was burning perilously low. The dim light splashed up the walls around us, lighting an area no wider than Nanny Pecks Sunday crinoline.

Della hugged Robbie against her dripping coat and stared at the fork in the tunnel. She shook her head. 'Either its all the same down here. It must go on for miles.

I splashed forward, my foot skidding on something hidden beneath the surface. It was shallow here at the sides of the passage. A deeper gulley carried a torrent of foaming, lump-flecked water out along the centre, but just ahead it split in two the rank water tumbling and gushing either side into twin arched black mouths.

I wiped the back of my hand across my face and instantly regretted it.

Five minutes back wed narrowly avoided a waterfall that came crashing down without warning from an overhead grille. We were lucky; any earlier and wed have been drenched, but that wouldnt have been the worst of it.

From the foul stink and it was a thousand times more noxious than the general air down here Id say it came direct from the tannery pits off Spread Eagle Street. As the deluge slammed down into the sewer, the raw, ripe smell of shit, piss, blood and rotting flesh made us retch. Our eyes burned and the insides of our mouths scorched like wed been sucking on cinders. The skin on my face and hands where the tannery water had spattered up stung like an open wound now.

I looked at the passages. The one on the right sloped downwards. If I was right and we had gone under the tannery pits off Spread Eagle Street back there, then the river wasnt far off. Surely the drain discharged itself into the Thames?

I blinked hard, my eyes were streaming from the fumes and whatever it was that had spattered up into them. I resisted the urge to rub them again. I rested my hand against the damp black bricks to steady myself and tried to imagine what might be above our heads, trying to picture the likely layout of the streets.

It was no good, the passage turned and twisted about so much I had as much idea of what direction we were taking as a mole at midday. I felt something brush against my ankle and looked down.

Della yelped as a pink-eyed rat the size of a well-fed cat skirted round me and disappeared into the passage on the right. We heard the scratching of its claws on the stones as it skittered away.

'Thats it, then we go that way. I splashed forward, but Della clutched my elbow.

'Youre not following that . . . that thing, are you?

'It has to go out into the world somewhere. You got any better ideas?

She didnt have time to answer. A metallic grating noise rang down the passage. It sounded like a bell had fallen through the floor of The Whitechapel Foundry and was rolling down the passage towards us. The scraping and clanging set every tooth in my head against its neighbour.

Then there came a deep rumbling sound. Moments later a torrent of water hurtled round the turn of the passage twenty foot back, slapping up against the wall in a great foaming wave.

I grabbed Della and pulled her up onto a ledge skirting the passage wall. We watched as the stinking scum-laced water gushed past us, tumbling like a river in spate down into the mouth of the right-hand tunnel. It kept on coming. I guessed that somewhere a sluice had been opened.

I pushed a matt of sodden hair back from my eyes. 'Looks like well be going left, then.

I didnt give her time to answer. I raised the lamp and waded into the entrance of the left-hand tunnel. Moments later I heard Della splash after me.

We walked in silence for a couple of minutes and I was glad to see the way the passage began to slope more keenly. The yellow water running down the centre seemed to take on a tumbling urgency that suggested it might know where it was going.

I turned to Della to remark on it, but she had stopped to look back the way wed come. Robbie watched me over her shoulder. I heard the skittering noise again and thought of those pallid bony feet scratching their way through the muck.

'There are rats everywhere down here. Im not going back if thats what youre thinking, Della Lennox. This is the right way. I can feel it.

I swung the lamp round and splashed on, my skirt weighed like plaster around my legs. The passage veered left. I put one hand on the wall to steady myself as I took the turn and slipped again on something greasy underfoot. I stopped dead.

The lamp showed up a circular space ahead with three passages running off it. But we couldnt get to them. A wide ribbon of shadow cut across the chamber floor. The sound of water falling from a height echoed from the bricks. I kicked forward to the lip of the ribbon and raised the lamp. The drain discharged over the edge of a brick precipice and fell thirty, perhaps forty, foot down to a frothing channel. The lamp showed up the jagged water-slicked edges of old masonry work and glinting black water below.

'Shit! I closed my eyes and took a deep breath. I swallowed down another lungful before turning back to Della. That was when I noticed the air tasted different here cleaner, almost fresh. I opened my eyes and looked again. The chamber was washed over in a thin grey light that had nothing to do with the lamp. The light came from above.

I tipped my head back and there it was another grille twenty foot up, only I could see stars and a tatty rag of cloud caught between the broken bars. The grille sat at the top of a brick-lined cone like a brewery chimney built underground. It was old, I could see patches where the masonry had crumbled away and where loose bricks jutted out from the wall, but there was a sort of ladder up there too, the rungs curved out from the wall and climbed up to that dish of faint grey light. I took another gulp of good air.

'I reckon we can get out here, Della. We made the right choice back there after all.

'I would say you have made the wrong choice, Kitty. And not only tonight.

The soft, sibilant words seemed to slice through the air. It wasnt Dellas voice.

I span around and felt the damp, freezing material of my dress press hard against my flesh.

It was like Id been drawn across a whetstone and opened out. Every sense was keen and raw as a January wind off the Thames. From the oyster cuts on my hands, to the tannery splashes that burned on my cheeks I was suddenly aware of every shrieking part of my body. I heard the smallest drop of water sliding off the walls, I saw the rainbow iridescence in the oily film of the tiniest bubbles of scum that tumbled past me in the drainage channel, and above the stench of sewer filth I smelt lemon cut with incense.

The cloaked figure threw back a hood. White blond hair caught the lamplight and shone like the moon against the slick black bricks of the passage.

'You? My tongue was like a lead weight in my mouth.