'Do you swear?'

'On my honour as a gentleman.'

'Haven't heard anyone say that for a long time.' Tate eased himself from the bed and pulled a hammer from underneath the mattress. 'We'll need this.'

'I don't understand.'

'It was a long hot summer. No rain from June the sixth until three weeks ago. Dried out all the river beds.'

'You mean they became passable? I thought the grilles stopped large objects, including people, from moving along the conduits.'

'Most grilles are rusty. Some are gone. Some are locked.' He pushed his hand into a syrup tin and pulled out a filthy set of long-stemmed keys.

'You can move under the streets?'

'I could. Now it's raining again. The channels have filled back up, but there are still ways.' He left the room with surprising speed, even though old injuries had twisted his body on damaged hinges. The pair of them headed out down the stairs and into the wet street like fugitives.

When they reached the wire fence of the alley at the end of Balaklava Street, Tate slipped through the gap and beckoned to Bryant. He stopped above the grating that Brewer Wilton had lowered himself into. 'Give me a hand.'

Tate groped about in the bushes for his iron T-rod, and together they eased the steel lid off the drain. The water level had risen since Bryant had examined it, and a dull roar of water could be heard in the distance. 'What's that noise?' he asked.

'Gospel Oak sluice emptying into the Regent basin.'

'But Gospel Oak is about half a mile away.'

'Sound carries down there.' Tate dropped to his knees in the mud and lowered the top half of his body into the hole. After a minute of searching, he emitted a grunt of satisfaction, withdrew the hammer and gave something in the hole a great whack. There followed a grinding metallic noise, and the rushing water seemed to ease off.

'What have you done?' asked Bryant.

'Obvious. Can't get down there if it's full. I'm diverting the flow.'

'You can do that?'

'Smooth as a knife. Go down.'

Bryant looked dubiously into the shaft. The cement floor was visible a few inches beneath the water now, but the rungs to it looked slippery.

'Want to show you something.'

'I'm a bit dicey on my pins.' Reluctantly, the elderly detective eased himself over the side of the drain, and began to climb down. They stood together on the draining concrete platform, heads ducked to avoid the low brick ceiling. The stench of rotting garbage and faeces settled into Bryant's nostrils and clothes, but beneath it was another smell, something he had not expected: the damp bite of green Thames water. The temperature was lower than at ground level. His breath plumed before him as he clicked on May's Valiant.

'Look.' Tate pointed through the olivine gloom at a pair of large oval holes on either side of the channel. The junction appeared deeper; water churned in a putrid eddy of cross-currents. 'The Prince of Wales Causeway. Six gates to close off before you reach the basin. Can't leave the gates shut more than a few minutes because of the pressure. Takes a logical mind to remember the sequence and survive.'

'The Water Board must know how to do it.'

'So do I.'

'You want us to go down there?'

'Not today, not with the forecast. Takes more than an hour, maybe two. Need waterproofs and a mask. Another day, if you want to know the reason.'

'What reason?' asked Bryant. 'What are you talking about?'

'Reason for all this upset. The water is where it began.'

To Bryant, it seemed the most inhospitable place imaginable. He wondered how the tramp could have slept on the platform without being besieged by nightmares.

'Come on, the rain's getting harder. Tunnel fills up fast. Drains off the Heath, through clay and brick, thousands of gallons in seconds. Get swept away and no one will ever find you again.'

Tate started to climb back up. He pulled himself out of the drain with ease, extending his shattered hand to Bryant. The pair were bonded by a secret now.

Back in the alley, he produced a muddy piece of card from his jacket and held it up. 'You need this.'

On it was printed a faded diagram designed like a Tube map, overlaid with the kind of Helvetica lettering popularized during the War. Instead of underground branch lines, it showed the paths of tributaries, each one variegated and named. Tate was holding the plan to a network of conduits. He tapped a calibrated thick line with his blackened forefinger. 'The Fleet. Each dot is a lock. Each line is a sealed gate.'

Bryant dug out his reading glasses and took a squint. 'According to this, you can't get as far as the Regent's Canal.'

'No, but you can branch off, all the way up to the York Road Basin. It was fine during the summer, you could walk along it, armed with the right keys. Now you have to divert each of the cross-courses as you go. As you said, the Water Board knows. They got the equipment. But I got all the keys.'

'You've done it?'

'A few of us.'

Bryant squinted through the drizzle that softened Tate's weathered face. 'Who are you?' he asked quietly. Tate's lips thinned, but a moment later the smile had vanished.

'I'm nobody,' he whispered sadly.

35

HUMAN NATURE

'I think our killer is using the underground tunnels,' Bryant explained, obliviously poking pedestrians with the tines of his umbrella as they dodged the puddles in Kentish Town High Street. 'He enters the alley from the back gardens and goes down into the water conduit. It passes right under the road and connects to the backs of all the houses on the east side.'

'Why would anyone go to so much trouble?' May was having difficulty keeping up with his partner this afternoon. A sense of angry urgency invaded Bryant whenever he was faced with the fallout from a preventable death. He and John had spent most of Friday with the shocked residents of Balaklava Street. Now they had left Aaron alone with his guilt in a searched, emptied and fingerprinted house, minus the person who had brought the rooms to life, and the world was expected to turn as usual. In the months following a death, the survivors saw small cruelties wherever they looked. It disturbed Bryant to recognize that the unit should have taken matters more seriously from the outset, and shamed him that they had achieved so little. It was the only time in the investigation when he had displayed any other emotion than a ghoulish enthusiasm. His revenge was to ignore his age and infirmities, to work harder than ever. It was when he needed to be watched most carefully.

'So that no one sees anything unusual in the street, obviously. Look how enclosed and overlooked it is. If you're well known in the area, witnesses are likely to remember you. It's someone Tate and probably all the others know by sight. That's why Tate didn't seem frightened when I talked to him. It's the unknown that scares people, the faceless stranger who attacks for no logical reason, because he's on drugs, or drunk, or just disturbed.' He thrust a crumpled paper bag at May. 'Have a pear drop.'

'You're taking a leap in the dark with this,' warned May. 'There's no reason to make such an assumption. The tramp has a history of mental problems, you said so yourself. He's an unreliable source of information. It might even be him.'

'And what would his motive be? Hang on, I want to get some sausages.' Bryant dragged his partner into the butcher's and tapped the cabinet. 'Are those Gloucester Old Spots fresh? They don't look it.'

'The oldest motive in the world,' May insisted, trying to concentrate. 'They have something he hasn't. Homes, money, security.'

'Then why doesn't he take anything? And why would he insist on showing me his escape route? Give me six Cumberlands and a couple of kidneys-nice fat ones, no rubbish.' He turned back to May while rooting inside his coat for money. 'Tate can't come out and admit what he knows. Perhaps he's afraid for his own life, so he's revealing how the deeds were done, trusting us to figure out the rest of it. But he knows more than he's telling, and that puts him in danger. It's your domino effect: each person with knowledge being systematically removed. Perhaps if Mr Bush had signed the Kyoto Treaty, this might never have happened.'

'Sorry, Arthur, you've lost me.'

'Climate change. The rivers dried out during the long hot summer, making them passable. Now all hell is breaking loose underground, because when it rains, the tunnels briefly turn into white-water rapids. None of the deaths occurred before the bad weather, did they? Perhaps that's because the conduits were too dry to dispose of any incriminating evidence. The killer patiently waited until the rain came back, providing him with a way of dumping anything that would link him to the murders. This is what the rivers were always used for. History repeats itself.'

'Really, Arthur, it all sounds very complicated.' May watched in some unease while the butcher chopped away at a pair of bulbous kidneys, wiping his bloody hands on his apron.

'I have to hang on to this, John; somehow it all comes back to the tributaries of the Fleet. Without the river there would be no houses. Without the houses there would be no murders. The first death is the key: a harmless old lady killed by water, because because of water, as though the killer was closing a circle, choosing a suitable punishment for her crime. Of course, it's possible we've completely misjudged what's going on. We may have to look at everything in a fresh light.' of water, as though the killer was closing a circle, choosing a suitable punishment for her crime. Of course, it's possible we've completely misjudged what's going on. We may have to look at everything in a fresh light.'

The butcher rang up Bryant's purchases. The elderly detective looked at his change in disgust. 'Is that all I get back from a tenner? Daylight robbery. Those pigs' ears look past their best. You shouldn't be selling things that look as if they've died of old age.' He snatched the plastic bag of meat and dragged May with him to the door.

'Another thing. That boyfriend of Kallie's-he's been away for weeks. Suppose he's been conked on the head and dropped down there, the murderer or an accomplice posting his cards from all over Europe? And what about the next-door neighbour, Heather? No one's seen her husband for ages. He's meant to be in Paris-what if he's actually floating about somewhere under King's Cross? And Benjamin Singh, he's supposed to be in Australia, but has anyone actually heard from him? Just how many men are missing from this damned street anyway? Wait, I forgot something.' He turned on his heel and headed back to the surprised butcher. 'Do you have any mutton? I may attempt a casserole.'

'I wish you'd slow down for a moment,' urged May. They were walking back to the unit because Bimsley and Banbury had taken the Rover to drop off evidence. 'Let's stop for refreshment, you can get your breath back.' He steered his partner into a Greek coffee shop.

'Two teas, one with lots of sugar.' Bryant glared at the listless girl playing with her hair behind the counter.

'We don't do tea,' mumbled the girl.

'Don't be ridiculous, it's the national drink, how can you not do tea?'

'Cappuccino, latte or espresso.'

'Those are Italian beverages. You're a Cypriot, surely,' Bryant barked, reluctantly moving to allow a pushchair past. 'You should have mint tea or little cups of Turkish coffee with half an inch of silt in the bottom. No tea! Good Lord, all you have to do is put some fresh leaves under boiled water.'

'Come on, Arthur, ease up a little.' May took his arm and led him to a table, then returned to order lattes.

'You realize if we hadn't started following Greenwood, we would never have made the connection?' said Bryant as his friend returned. 'Everyone knows about the London Tube map; why isn't this other one public knowledge? Who else is in possession of it?' He slapped the underground tunnel plan on the table between them. 'The city functions in much the same way as its streets-every time you think you have something figured out it twists back on you. The answer has to be here in these numbered conduits . . .'

'No, it isn't, Arthur. I've seen you like this before, and to be honest, I think you've got the wrong end of the stick, or possibly the wrong stick entirely. The only answer you'll get is by talking to people. You don't observe, you don't think about human nature.'

'I have you to do that for me.'

May sighed. 'Look at the girl behind the counter, the one you just had a go at. What do you see?'

Bryant squinted over. 'A fat Greek schoolgirl who needs a few lessons in civility.'

'Try again. Her name's Athena and she's about nineteen; she's married with two children, and she has a younger sister. Her father owns the place, and she's working here against her will. Her husband got drunk last night and they had a fight. She's trapped and miserable, and wondering how her life turned out like this.'

'You worked that out from watching her?' asked Bryant, genuinely interested.

'It's not difficult,' said May. 'She's wearing a wedding ring. Look at the photos on the walls behind her: family pictures taken in Cyprus-mother and father, no sons featured. The owner has given his oldest daughter a job because she needs it. Why? Her children are twins. The man who went past with the double pushchair spoke to her by name. He's ginger, from around here. You see his type everywhere. Got into fatherhood too early, and to his dismay finds himself taking care of not one but two small girls-very angry about it. You don't have to be a genius to read the disappointment in his face. Wouldn't work here because it's not a man's job, and besides, the place belongs to her family, which means he would fight with them all the time. She puts in long hours, he puts the kids to bed and goes to the pub. She plays with her hair to cover a bruise. Facial marks like that are rarely self-inflicted. She's trapped between controlling parents and an embittered partner, so she's not really too bothered about whether you get tea, coffee or rat poison.'

'Hmm.' Bryant stirred his cup thoughtfully. 'Perhaps you're right. I should pay more attention to people. Get my nose out of my books once in a while. I do like them, you know-people. It just seems as if I don't.'

'I know,' said May gently. 'You have a good heart, but you don't reveal it very often. As a suspect, Aaron's a non-starter; even you can see that. Tate is the closest we have. I think the first thing we need to do is put a watch on him. No one's been dropped into the sewers, we'd have found drag marks in the gardens or the alleyway, but I agree that it may explain the lack of incriminating evidence. We have no weapons beyond a sheet of clingfilm. You have to admit that's unusual. But you also have to admit that there's another possibility.'

'Which is?'

'You've allowed this whole situation with Greenwood to affect your instincts about Balaklava Street. You love collecting arcane knowledge about underground rivers, so suddenly they have to feature in an entirely separate investigation.'

'The thought had crossed my mind, but you you have to admit it's a damned coincidence that Balaklava Street is built over a tributary. Have you decided what you're going to do about Sunday night?' have to admit it's a damned coincidence that Balaklava Street is built over a tributary. Have you decided what you're going to do about Sunday night?'

'I thought you and Mangeshkar could keep an eye on Greenwood and Ubeda. Whatever they're planning has to end then, because we start fresh the next morning, whatever happens. Even Raymond agrees that we have a legitimate reason for putting more resources into Balaklava Street now. Meanwhile, post Bimsley at the hostel to make sure Tate doesn't go anywhere. I'll go and see Monica.'

'So I get posted somewhere cold, damp and possibly lethal to a man of my advanced years while you pitch woo to a married woman,' Bryant harrumphed, clattering a sugar lump against his false teeth. 'I suppose I can't blame you. You need affection and reassurance more than I.' Bryant had decided a long time ago that he was far too strange to find anyone who would love him. He had, of course, underestimated the bravery and tenacity of the British female, but now he was convinced that he had left it too late, and had resigned himself to the consolations of work and friendship. 'Still, I think it would be better if we followed Greenwood together. He knows you.'

'I can't be in two places at once. And you're not coming with me to see Monica.'

'So you are are planning to woo her.' planning to woo her.'

'Nobody says "woo" any more, Arthur. You're so Victorian.'

'Stop saying that, it's just that there are certain modern habits of which I disapprove. Wet liberals, stealth taxes, the seduction of married women, telephone sales and hamburger outlets spring to mind.'

They remained in the coffee shop as it grew dark, watching the raindrops meandering down the window panes like a million silver comets.

36

BLOWBACK

The passageway was lined with small dun-coloured paintings. May had noticed them on his last visit, but the light had been too low to discern any detail. The wall sconces had no lightbulbs in them. 'We never replace them,' explained Monica.

'But you can't see the pictures.'

'Exactly so. There's a light here somewhere.' She struck a match to a candle and held it aloft. 'Now do you see?'

May found himself looking at several studies, roughs and pencil sketches for Pre-Raphaelite paintings. 'I don't understand,' he murmured, watching as the coppery lines wavered in the candlelight. 'These are beautiful.'

'My husband thinks they're worthless. He has an old-school attitude to Pre-Raphaelites that won't allow him to see beyond the detailed textures to the beauty of intent. So, as a mark of rebuke, to those artists and to me, for having too much materialism, too much sentiment and so little taste, he insists that we leave them hanging here in the basement. The walls are getting damp, and many of the sketches have started to stain. The house isn't alarmed, of course-we refuse to become prisoners in our own home, apparently-so I compromised by removing all the lightbulbs. That way, if we're burgled, the thieves will miss the best pieces in the house. And so another small battle is fought and drawn.'

'Why do you stay with him?' asked May. 'He limits your freedom and makes you unhappy.'

'God knows we certainly like different things. He's Berlin and Bauhaus and brutalism, I'm Turner and Tate Britain. But nothing's that simple, is it? The children are in their nightmare years, veering between innocence and arrogance in a way that makes me fear daily for their lives. Gareth's colleagues virtually dictate how to spend our finances. The paths of our lives seem set in concrete. Do you remember before you had to be grown-up every second of the day, John? How it always felt like morning?' She lowered the candle, and light faded from the gilt frames. Tiny lines appeared on her face, like the craquelure on a painted heroine. 'Now it always feels late in the day. Shadows are gathering, and the best pleasures feel far behind me. Gareth is looking for something he can never have and will never find: respect. I can't help him, so instead I am a hindrance, or an embarrassment. He'll make a fool of himself-or worse, break the law and be disgraced, his expertise ridiculed, his judgement dismissed. And it will kill him, because he has nothing else left.'

Back in her studio, she turned on the radiator and poured tall whiskies. 'He's become indiscreet of late, leaves books and maps lying all over the lounge. But I still have no idea what this ridiculous quest is all about, and nothing I say can change his mind.'

'I can tell you what we know,' said May, 'because I hope tonight will see the end of it. There's something called The Vessel of All Counted Sorrows-an Egyptian alabaster vase like a death urn, intended to represent the woes of the world. It occupies a key place in pre-Christian mythology, but is as likely to exist in a tangible form as the Holy Grail.'