With the time past midnight, Ben and Trajan took a taxi down to Embankment, that swathe of valuable real estate reclaimed from the Thames a couple of centuries ago. Where there had once been muddy banks, a major road now ran between the water and some of the capital's most prestigious buildings. The summer night was a warm one, and people were heading home either on foot or by car after visiting the restaurants and theatres. Reflected lights shone on the high tide as a gaudy party boat drifted downstream to the accompaniment of a band playing on its stern deck.

After paying the taxi driver Ben followed Trajan to the wall that separated the path from the river. Even in the street lights it was easy to make out the rust-coloured smudge on the back of the man's blond head that marked the position of the wound.

'How are you feeling?' Ben asked.

'Fine. Are we close to where I first met you?' The man appeared tense now, as if unsure he could handle any memories if they should come rushing back at him.

'Just along there near the road sign. I was looking at the river when April came up behind me.' Ben gave a faint smile. 'At first I thought someone was going to chuck me in the water.'

Trajan scanned the roadway. 'It's well lit, and you can see right down toward Cleopatra's Needle. After you left us, did you look back?'

Ben shook his head. 'By that time I was in a hurry to get home.' He also remembered the profound disappointment at realizing that April Connor was moving in with the blond man who had a well-paid career in shipping. He noticed Trajan was staring down at the stone path as he walked alongside the wall. 'See anything?'

'Not yet. I'm looking for my blood. If I see where I spilt it from thisa' He touched the wound. 'Then I'll know exactly where the attack took place.'

'There was heavy rain last night, Trajan. I doubt if you'll find anything.'

'I've got to try, d.a.m.n it. What else can I do?'

'You don't remember anything about the attack itself? How you were struck? Or if there was a weapon?'

'I remember figures on the wall - they were odd for some reason.'

'Figures? Before you only mentioned one.'

Trajan blinked. 'Twoa I'm sure there were two. But only one attacked us.'

'There was a weapon?'

He rubbed his forehead. 'Noa I don't remember. I just realized later that I was riding in a taxi with blood soaking my hair. d.a.m.na'

'No smells? Aftershave? Cooked food? Beer?'

'No! Give it a rest, Ben.'

'A big man? Thin? Plump? Tattoos?'

'd.a.m.n it, whatever happened was knocked clean out of my head when he threw me.'

'Threw you?'

A flicker of surprise ran across Trajan's face. 'He never hit me. He picked me up and threw me away like I was a piece of c.r.a.p.'

'It's coming back, Trajan. You're starting to remember. What did he do to April?'

'I don't know.'

'Bit her?'

'Shut up, Ben. Stop pushing me. Give me a chance to-'

'Forget again. Come on, you lazy b.a.s.t.a.r.d.' Fury surged through Ben. 'Think harder. April's life might depend on it.'

'I am thinking, you b.l.o.o.d.y-'

'Well, think harder. Burst a few brain cells.'

'Shut up.'

'You're safe and sound. April isn't.'

Trajan whirled round and shoved Ben against the river wall. Rage blazed in his eyes, and that aura of violence that hung over London all evening threatened to find its focus right there and then.

'See, you're no weakling,' Ben panted. 'You've got muscle; so the guy who put you on the ground must have been strong as a bull.' Ben tried to push the man back but Trajan froze as he stared over Ben's shoulder. 'What's wrong?'

'There's someone in the river.'

'What?'

'There, under the pier.'

'Okay, let go. I want to look.' Ben shrugged himself free then turned his attention to the timber structure that ran out into the water to one of the ferries that had been moored up for the night.

'Someone in the water?' Ben asked as he stared into the shadows. 'Male or female?'

Trajan shrugged. 'Forget it. It's just some kid spraying graffiti.'

Ben moved to his right until the timber bollard that blocked his view was out of the way. There, standing on a beam beneath the pier decking, was the figure of a man. Across the white flank of the ferry boat he was busily painting these words: VAMPIRE SHARKZ.

* They're coming to get you *

EIGHTEEN.

Ben hissed, 'Trajan, cut off his retreat from that end of the pier. I'll catch him from this side.'

The blond man was stunned. 'Catch him? Why do you want to catch some vandal daubing graffiti?'

'Come on, before he vanishes.'

Trajan stayed where he was on the embankment walkway. 'We're searching for April, we don't have time to stop someone painting their name on a boat.'

'Quick, Trajan. As soon as he finishes he'll vanish again.' Ben walked as quietly as he could along the pier as the man, who'd been painting the mysterious slogan 'Vampire Sharkz: They're Coming To Get You', added the twin red spots that served as eyes for the smiley face. As he painted there in the shadows beneath the pier a reddish mist drifted from the aerosol, which he used to create his unlawful art.

Trajan has good night vision, Ben realized. Not many people would notice the man in his black sweater and jeans at work there. Even with street lights the figure was simply another shadow amid many shadows. From what Ben could make out the man stood on one of the beams that supported the jetty structure. Just below him was the surface of the river. The currents were strong and bore branches, bottles, paper cups and other jetsam at a h.e.l.l of a rate. Moreover, the direction of the flow was upstream, so this was the mighty tidal surge that swept inland. Even as Ben watched he saw that the level of the water crept up towards the man's feet. No doubt the rising tide was an incentive to finish his Vampire Sharkz message quickly before he escaped back to dry land. After all, he only had to slip.

As Ben padded along the pier towards the jetty a hand grabbed his forearm.

'I can't let you do this,' Trajan told him. 'I don't know what that man means to you, but we must find April.'

'Let go of me. He'll get away.'

'No.'

'd.a.m.n it, Trajan. See that guy? He's haunted London for the last three months. His graffiti's everywhere.'

'So?'

'Don't you understand? If whoever attacked you makes a habit of it then our painter down there might have seen something.'

Trajan was doubtful. 'You think-'

Ben slipped from the muscular grasp then moved along the jetty. Too late. The second Ben started to climb over the rail the artist moved with the speed of a cat. He shot over the rail on to the platform and sped noiselessly across the boards towards the pier, which would take him back to sh.o.r.e. Then he'd vanish into the streets in the blink of an eye.

Only Trajan was there. The big man blocked the narrow gantry. When the artist saw there was no exit that way he ran back on to the jetty to be confronted by Ben.

In front of Ben was a slightly built guy of around thirty with a crooked nose and dark brown eyes beneath a ma.s.s of curly black hair.

The man held up the aerosol, showing he was armed with nothing more lethal than paint. 'Okay, okay.' His words were a gabble. 'My name is Spiro Akinedes. This is my first offence. I'll do as you say.'

'Mr Akinedes,' Ben began. 'We're not the police.'

'No?'

'I just want to talk to you.'

'You own the boat?'

'The one you've just decorated?' Ben shook his head.

'Then you'll let me go?'

'As soon as we've talked.'

'I'm not interested in talking.'

'Then I'm not interested in letting you go.' Ben made his voice tougher. 'And if you don't talk we'll take you to the nearest police station.'

'You wouldn't do that.'

'You're a famous graffiti artist, Mr Akinedes. The police have been looking for you for weeks.'

'What do you want to know?'

Trajan was mystified, but stayed quiet. Ben realized that suggesting this individual might know something about April's disappearance was riotously optimistic to say the least. And yeta in the back of Ben's mind was the cryptic conversation with the hermit in his boat on a pole near Tower Bridge. Elmo Kigoma had urged Ben to uncover the meaning of the Vampire Sharkz graffiti then write about it. All this - the graffiti, April's disappearance, the hermit's veiled warnings - suddenly appeared to be linked. It resembled one of those puzzles made up of random shapes that appeared to be on the verge of fitting together to create a recognizable picture. Ben knew he needed to acc.u.mulate enough facts and the answer to all these puzzling clues would fit together and make a coherent whole. Even though he'd been commissioned by his editor to find this mystery graffiti artist the story had vanished from Ben's radar. All that interested him was finding April Connor and, by the most slender of possibilities, Spiro Akinedes might know some tiny but vital fact. Meanwhile, the man cast wary glances; standing in one place for too long made him uneasy.

Ben asked, 'What's it mean?'

The man turned the aerosol over in his hands, while his brown eyes bulged with fear.

'Ben.' Trajan sighed. 'This gentlemen can't help you. Let him go.'

'He can go,' Ben agreed. 'I just need a moment of his time.' He glanced at the red graffiti on the side of the boat. 'Vampire Sharkz: They're coming to get you. Is that a threat or a promise or a prophecy?'

'It's just a thing I do,' the man replied with a shrug.

'For just a thing that you do you've worked b.l.o.o.d.y hard at it. How many times have you painted it? A thousand? Two thousand?'

The man's eyes became pained as if he didn't want to be reminded. 'Oh, plenty.'

'Then you have a good reason, Mr Akinedes?'

He gave a grim nod.

'That logo and the smiling faces are all over London.' Ben walked across the jetty boards. 'You don't just paint something like that on an idle whim, do you?'

'Leave him alone, Ben,' Trajan said. 'Can't you see he's scared?'

Ben kept an unwavering eye on the artist. 'Scared? What of? Vampire Sharkz?'

'I need to go now, Mistera'

'Call me Ben. So what's troubling you?'

'Shoes!' The word burst from his lips as if to betray him.

The response caught Ben by surprise. 'Shoes? What's wrong with my shoes?'

'You're walking where I've got to work.' Spiro Akinedes spoke as if it was the last thing he wanted, only the words spilled out by themselves. 'Pleasea the soles of shoes are covered with bacteria, viral contaminationa just so dirty.' He gulped. 'You've got to keep your shoes away from this part here.' He gestured a portion of the decking, then added, 'Show me the bottom of your shoes.'

Ben obliged, lifting one foot then the other.

'Thank you,' the man said with a sigh of relief. 'You can never be sure. You might have stepped in somethinga you know, dog faeces, they can have a worm thata' He gestured near his face. 'Feeds on the eyes. Blinding.'

Trajan began, 'Ben, I think the gentlemen's-'

'No, I'm not mad.' In the dim light he abruptly crouched down, shook the aerosol, and began to spray on to the planking; the first letter was a distinctive V. 'If you must know I suffer from OCD. Obsessive Compulsive Disorder. It's related to anxiety disorders - had it since I was a kid. If you're in the grip of OCD you're trapped by repet.i.tive thoughts and bizarre habits. It's not madness. More than two per cent of the population suffer from it.' He worked the aerosol; its atomizer jetted a stream of red on to the timber. V-A-M-P. 'The habits are senseless, distracting; OCD sufferers realize they're locked into irrational behavior patterns, but they find it difficult to break outa often they don'ta usually they accommodate it.' He finished VAMPIRE. 'Symptoms of OCD are obsessional ideas and compulsive behavior - including endless hand washing, arranging household ornaments into special patterns, then checking, and re-checking, for hours on end. Fear of dirt.' The words cascaded from him like a heartfelt confession. By now he'd sprayed VAMPIRE SHARKZ.

Trajan impatiently tapped the handrail. 'Ben, leave him. This is getting us nowhere.'

'Just give me another minute. I'm on to something.'