He went to the shelves of books in an alcove, took three out and opened a flap behind, removing a Walther PPK with a silencer already fitted. He replaced the books, checked the weapon and put it into the waistband of his jeans, snug against the small of his back.

He took the umbrella when he left the house, for the rain was relentless, and lifted the garage door, where an old Mini Cooper in British racing green waited. The perfect town car, so small and yet capable of over a hundred with the foot down. He got in, drove to the end of the mews and paused to light a cigarette.

'Right, you bastard, let's see how you're doing,' and he drove away.

At the same moment, Helen Lang, dozing on the couch, came awake, aware of Tim Pat Ryan's face, the last photo she had looked at in the file. She sat up, face damp with sweat, aware that in the dream he had been hurting her, laughing sarcastically. She stood up, went to the desk and stared down at the open file, and Tim Pat Ryan looked back at her.

She picked up the Colt and weighed it in her hand. There was an inevitability to things now. She stood in the hall, pulled on a trenchcoat and rain hat, opened the shoulder bag that hung on the hall stand, found some cash, then put the Colt in her pocket, took down her umbrella and let herself out.

She hurried along South Audley Street, the umbrella protecting her from the driving rain, intending to go to the Dorchester nearby. There were always cabs there, but as it happened, one came along on the other side of the road. She waved him down and darted across.

' Wapping High Street,' she said, as she climbed inside. 'You can drop me by the George,' and she sat back, tense and excited.

Hedley had retired with no intention of sleeping, had simply sat in an armchair in the basement flat in the darkness, for some reason afraid for her. He had heard her footsteps in the hall, was up and waiting at the foot of the stairs. As the front door opened and closed, he grabbed his jacket, went up and had the door open. He saw her hurrying along the pavement, the umbrella bobbing, the wave of the hand for the cab. He'd left the Mercedes at the kerb, and was at it in an instant and switched it on. As the cab passed on the other side of the road, he went after it.

Dillon reached the Tower of London, St Katherine's Way, and moved into Wapping High Street. He passed the George Hotel, turning into a maze of side streets and finally parked on a deadend turning. He got out, locked the door and walked rapidly between the tall decaying warehouses, finally turning on to China Wharf. There were few ships now, only the occasional barge, long disused cranes looming into the sky.

The Sailor was at the end beyond the old quay. He checked his watch. Midnight. Long past closing time. When he paused in the shadows, the kitchen door at one side opened, light flooding out. Tim Pat Ryan and a woman.

'See you tomorrow, Rosie.'

He kissed her cheek and she walked away rapidly, passing

Dillon safe in the shadows. He moved to the nearest window and peered in. Ryan was sitting at the bar with a glass of beer, reading a newspaper, totally alone. Dillon eased open the kitchen door and entered.

The saloon was very old-fashioned and ornate with a mahogany bar and gilded angels on either side of a great mirror, for the Sailor dated from Victorian times, when sailing ships had moved up the Thames by the dozen each day to tie up and unload at the quay. There were rows of bottles on glass shelves, beer pumps with ivory handles. Ryan was proud of it and kept it in apple-pie order. He loved it like this at night, all alone, reading the Standard in the quiet. There was a slight eerie creaking of a door hinge, a draught of air that lifted the paper. He turned and Dillon entered the bar.

'God save the good work,' Dillon said cheerfully. 'There's hope for the world yet. You can actually read.'

Ryan's face was like stone. 'What do you want, Dillon?'

' "God save you kindly" was the answer to that,' Dillon said. 'And you an Irishman and not knowing.'

'You've no right to be here. I'm clean.'

'Never in a thousand years.'

Ryan stood and opened his jacket. 'Try me. I'm not carrying.'

'I know. You're too clever for that.'

'You've no right to be here. You're not even Scotland Yard.'

'Granted, but I'm something more. Your own worst nightmare.'

'Get out now.'

'Before you throw me out? I don't think so.' Dillon lifted the bar flap, went behind, reached for a bottle of Bushmills and a glass and filled it. 'I won't drink with a piece of dung like you, but I'll have one for myself. It's cold outside.'

Without a flicker of emotion, Ryan said, 'I could call the police.'

'What for? I'm not carrying myself,' Dillon smiled as he lied. 'You see, old son, this is a new agenda, what with the Northern Ireland Secretary, Sinn Fein and the Loyalists with their heads together in Belfast working away at the peace process. I mean, who needs guns any more? My boss wouldn't like it.'

'What do you want?' Ryan asked. 'What is this? You've been on my back for years.'

'Just making my rounds,' Dillon said. 'Just to let you know I'm still on your case. The Semtex you supplied the Birmingham and London units – how many bombings was it used for? Three? Four housewives in that shopping mall in Birmingham. We know it was you, we just can't prove it. Yet.'

'You can talk. How many did you kill for the cause? For nearly twenty years, Dillon, until you turned traitor.'

'But I never sold drugs or used young girls for prostitution,' Dillon said. 'There's a difference.' He swallowed the rest of the Bushmills and put the glass down. 'It's cold outside and dark and I'll always be there in the shadows. To vary an old IRA saying, my day will come.'

He turned and walked to the kitchen door and Ryan exploded. 'Fuck you, Dillon, fuck you. I'm Tim Pat Ryan. I'm the man. You can't treat me like this,' but the kitchen door was already closing softly.

Ryan, beside himself with rage now, hurled back the flap, opened the old-fashioned cash register, fumbled at the back of the drawer and found the Smith amp; Wesson. 38 pistol he always kept there fully loaded, turned and headed for the kitchen.

Lady Helen Lang had paid off the cab outside the George Hotel in Wapping High Street. Remembering the street map, she crossed the road and turned into a narrow lane. Hedley, caught behind two cars at a red light, saw her go. He swore softly, took off on the green and moved into the same lane. But there was no sign of her, even when he turned his lights on fully. It was a maze of decaying warehouses and narrow criss -crossing streets. What in the hell was she playing at in a place like this? Frantic with worry, he started to cruise slowly.

Lady Helen, her umbrella high against the teeming rain, found China Wharf with no trouble. There was a light at the pub window and an old-fashioned gas lamp bracketed to the wall above the painted sign that said the Sailor. It threw a diffused light to the edge of the wharf, the river black beyond, lights on the far side. She hesitated, uncertain now. A large Range Rover was parked close to the pub entrance, Ryan's, probably.

She stood in the umbrella's shelter and the kitchen door opened and Dillon came out. She recognized him at once from the file, and, surprised, she drew back. She watched him walk across the wharf and light a cigarette, then the kitchen door opened again and Tim Pat Ryan, also unmistakable, rushed out.

'Dillon, you bastard,' he called, and in the light she saw the Smith amp; Wesson. 'Here's for you.'

Dillon laughed. 'You couldn't hit a barn door, you never could. Someone always had to do it for you.'

His hand found the butt of the Walther and he drew it, crouching as Ryan fired wildly. Dillon put a foot forward to steady himself, but there was a puddle of spilled oil there, and he slipped, falling headlong, the Walther skidding away.