'Perhaps you'll come up with something over there,' Ferguson said.

'I always believe in travelling hopefully.' Dillon poured him a glass of Cristal. 'Mind you, one thing does intrigue me.'

'What would that be?'

'We know all these facts about the whole Sons of Erin business and yet the Secret Intelligence Service knows nothing. Just the usual stuff on Barry, but nothing more. A great big blank. It smells to me of one of those it-didn't-happen jobs as far as Simon Carter and company are concerned.'

'You could be right.'

'I always am,' Dillon said.

In his office in the Basement, Blake sat thinking. Finally, he pressed a buzzer for Alice. She came in and sat down.

'You look as if you've got a problem.'

'The leak. The White House leak. There has to be more we can do on it.'

'So you don't have much faith in the chief of staff's efforts?'

'It's not that. I just feel we're missing something. Look, Alice, say you're the Connection. The Sons of Erin are all gone. You're left with one person to talk to -Jack Barry.'

'So?'

'So remember when we tracked down that Pentagon spy a couple of years ago? Patterson?'

Comprehension dawned. 'You mean Synod?'

'Exactly. Why not set the Synod computer to tracking some calls. Insert the name Jack Barry. See what crops up.'

'We're tracking Northern Ireland?'

'No, I would suspect coded mobiles at that end, so that's no good. Stick with Barry and see what comes up. The White House first, then Washington.'

'Millions of calls, Blake. That's what Synod covers.'

'But it will tell us where any calls to someone called Barry originate from. Let's try it, Alice. What have we got to lose?'

In Washington, Thornton phoned Barry. 'I have more intelligence for you. Blake Johnson managed to track down a young woman in New York with quite a story.' 'Well, tell me.' Which Thornton did.

When he was finished, Barry said, 'The old bitch, just let me get my hands on her.'

'Don't get so worked up. You don't even know who she is.'

'Neither do you.'

'And neither does Johnson nor the President nor your old pal Dillon in London. By the way, Dillon is due here soon, to see if he can recognize the woman from security videos.'

'I keep wondering how you know all this.'

'I've told you before, I have my sources. You let me worry about my end. Just you worry about your own.'

'All right. So what about the woman?'

'Leave it with me. Maybe I can come up with something.'

That evening, Thornton started to trawl his computer. He had the ability to access most things, probably anything when he had the time. To start with, he went into CIA records of Protestant Loyalist paramilitary groups in Northern Ireland. He ran Jack Barry through, as well as every IRA and Sinn Fein activist from Gerry Adams to Martin McGuinness.

Jack Barry had spent a lot of time in the Middle East, was known to have visited the States under three false names during the same period. This still left what had happened to the Sons of Erin, from Tim Pat Ryan to Senator Cohan. There was no way of denying a deliberate campaign to wipe them out.

Why would that be? He nodded to himself. Vengeance, but for what reason? What could they have been responsible for? He thought about it and the one thing that made sense was what the woman had said to Barry: you butchered my son in Ulster three years ago, executed his friends, four of them, including a woman.

He went back three years earlier on the computer, looking for information to the White House from Brit Intelligence and then he remembered. His first big coup. The undercover group in Ulster. In those halcyon days, the Brits had been encouraged by their own government to give the fullest information to the White House. The information had streamed in and was only one of many things he had passed on to Barry. He returned to the computer, tapped the keys and brought it all back.

Jason, a lieutenant in the Marine Commandos, shot in Londonderry. Archer, a lieutenant in the Military Police, a car bomb in Omagh. There was a woman lieutenant, also Royal Military Police, shot in the street in Belfast. A young acting captain of infantry, chosen apparently because his mother was from Ulster.

Which left one. Thornton sat there thinking about it, then tried the fifth member of the group and its commander. Major Peter Lang, Scots Guards and SAS, killed in South Armagh by a car bomb of such devastating power that no body had ever been discovered. He sat there thinking about it and knew he was on to something, reached for the phone and rang Barry's coded mobile.

Barry, asleep, came awake churlishly. 'Who is this?'

'Tell me,' Thornton said. 'The undercover group of Brit officers you took out three years ago.'

'What is this?'

'The woman said you butchered her son and executed four more, including a woman. I've just remembered myself. I sent you the information in the good old days when the Brits trusted us.'

Barry sat up. 'I remember now.'

'And the commander, a Major Peter Lang? According to the records, he was killed by a car bomb so big that even his bits and pieces were never recovered.'

Barry reached for a cigarette. 'He didn't die in a car bomb. We blew his car up with a big charge to confuse the opposition.'

'What did you do?'

'What do you want to know for? You never asked for details then.'

'It's important. Tell me.'

'He was very English upper-class, a hard bastard. Got him coming out of a pub. One of the lads had served in the Scots Guards and recognized him.'

'What did you do?'

'Put the screws on him. It's all coming back. He had a great South Armagh accent. I mean, it all stank to high heaven.'

'So you tortured him?'

'Something like that.' Barry snapped. 'What's so special with this guy?'

'And why did you blow up his car and pretend?'

Barry laughed. 'The boys left him in such a mess, we put him through this big concrete mixer we found on a motorway bypass they were building in the area.'

The thought of it was so nauseating that even Thornton had to catch his breath.

'What's so important?' Barry asked.

'I might be on to something. I'll phone you back.' Thornton rang off.

He went back to Peter Lang, Scots Guards, SAS, Military Cross for unspecified reasons, the father, Sir Roger Lang, a colonel in the Scots Guards. Then came the information that took his breath away. The mother was Lady Helen Lang, an American citizen, born in Boston. The rest of the details flowed across the computer screen. Her companies, her immense wealth. Her addresses in London and Norfolk. There was even an end piece on her chauffeur, a Vietnam vet.

Thornton sat there, staring at the screen, then went to a cupboard, found a bottle of Southern Comfort, and poured a large one. He went to the window, savouring the drink, and looked out at what had turned into an evening of rain and sleet. One thing was certain. He had found the mystery woman.

Barry had got out of bed at the safe house in County Down, found a robe and made tea in the kitchen. He was working his way through the previous day's Belfast Telegraph when the phone went again.

'Just shut up and listen,' Thornton said. 'You killed Major Peter Lang of the Scots Guards and SAS. His father was Sir Roger Lang, Scots Guards, and his wife – and this is the good bit – was Lady Helen Lang. I think she's the woman who's spoken to you, the one who said you butchered her son. It all fits: the timing, the identity of the other four.'

Barry exploded. 'The bitch. She's dead meat. What I did to her son is nothing to what she gets.'

'Okay, don't go through the roof. What will you do?'

'Where does she hang out?'

' London and Norfolk.' Thornton gave him the addresses.

Barry said, 'I'll check out where she's going to be. I've friends in London who'll handle that.'