Lindsay raked around in her desk drawer until she found a blank cassette. Going through to the large L-shaped living room where the stereo system with the twin tape decks occupied a corner, she set it up to make a copy of the computer tape and sprawled on one of the elegant grey leather chesterfields while she waited for the recording to finish. It was wonderful to lie back on the comfortable sofa surrounded by the restful atmosphere created by Cordelia's unerring talent for interior design, though she felt a pang of guilt when she remembered the squalid conditions back at Brownlow. Lindsay ruefully recalled her feelings when she had first entered Cordelia's domain two years before. She had been overwhelmed with the luxurious interior of the tall house by the park, and it had been months before she got out of the habit of pricing everything around her with a sense of puritanical outrage. Now, it was her home, far more than her Glasgow flat which she rented out to students at a rent that covered her overheads.

She turned over again what Rigano had said. As far as the blond man was concerned, it seemed plain to Lindsay that he was something to do with intelligence, since Rigano had denied so vehemently that he was SB while pointedly ignoring her MI5 allegation. And if Stone wasn't following her, that didn't leave many options for the focus of his interests. And that in turn meant she wasn't barking up the wrong tree as far as the existence of wider political implications was concerned. What she couldn't understand was why Rigano was just sitting back and letting it happen without pursuing the same person that she was interested in.

Unless, of course, she was completely wrong, and the two strands were unrelated, leaving the murder as a purely personal matter. That would leave the ball firmly in the court of Warminster, Mallard and the putative biker, or Alexandra Carlton. The interest of the security forces could then be explained away as concern about police action jeopardizing some operation of theirs. Since Lindsay was still far from clear about the point of killing Rupert Crabtree, either option seemed possible. However, the attempt on Deborah's life seemed logical only if one assumed that it had been made to silence her. And if that was the case, Lindsay argued to herself, how did the murderer know that Debs hadn't already spilled whatever beans she possessed? And if she hadn't, then was she likely to do so now, especially since her silence must have come not from fear but from a failure to recognize what she knew or its importance? Lindsay shook her head vigorously. She was going round in circles.

She mentally replayed her conversation with Rigano again. Something he had said as a throwaway line came back into sharp focus. "It's about people carrying offensive weapons for mistaken notions of self-defense," he had remarked bitterly. Suddenly the jigsaw fell into place. Lindsay jumped to her feet and went to the phone. If Cordelia had been accessible, she would have outlined her theory then and there and waited for the holes to be picked in it. Failing that, she punched in the number of Fordham police station and drummed her fingers impatiently till the connection was made.

"Hello... Can I speak to Superintendent Rigano?" she demanded. The usual sequence of clicks and hollow silences followed. Then the switchboard operator came back to her and reported that Rigano was out of the building. But Lindsay was not to be deflected.

"Can you get a message to him, please? Will you tell him that Lindsay Gordon rang and needs to talk to him urgently? I'm just setting off to drive to Fordham now, and I'll be at the police station in about an hour and a half; say five o'clock. If he's not back by then, I'll hang on. Got that?"

The woman on the switchboard seemed slightly bemused by Lindsay's bulldozer tactics, but she dutifully repeated the message and promised it would be passed on over the radio. Taking the original cassette tape out of the machine and stuffing it in her pocket, Lindsay left the house, completely forgetting the flashing answering machine and her promise to Cordelia.

She walked round to the mews garage where she kept the car and was soon weaving through the traffic, seeing every gap in the cars ahead as a potential opportunity for queue jumping. Excited as she was by the new shape her thoughts had taken, she forced herself not to think about murder and its motives while she negotiated the busy roads leading to the M4.

She arrived at Fordham police station ten minutes ahead of schedule. The elderly constable on reception desk duty told her Rigano was due back within the next half hour and that he was expecting her. She was taken through to a small anteroom near his office and a matronly policewoman brought her a cup of tea, freshly brewed but strong. Lindsay found it hard to sit still and chain-smoked through the twenty minutes she was kept waiting. She looked at one cigarette ruefully as she blew smoke at the ceiling. No matter how hard she tried to give up or cut down, at the first crisis she leapt for the nicotine with the desperate fixation of the alcoholic for the bottle.

Rigano himself came to escort her to his room. More cheerful now, there was no sign that he resented her demand to see him. But he seemed determined to keep a distance between them. In his office, there was no sign of his sergeant or any of the other officers to take notes of the interview. Lindsay was disconcerted by that, but nevertheless relieved. What she had to say didn't need a big audience. And if some hard things were going to be said on both sides, it was probably just as well that they should go unrecorded.

"Well," he said, indicating a chair to her as he walked round his desk to sit down. "You seem in a big rush to talk to me now, when you could barely spare me a sentence earlier on. What's caused the big thaw? Surely not my overwhelming charm."

"Partly it's fear," she replied. "I said to you earlier that I'd be a fool if I knew who had killed Crabtree and tried to kill Deborah and persisted in keeping my mouth shut. Well, I think that now I know, and I'm ready to talk."

If she expected him to show signs of amazement or shock, she was disappointed. His eyebrows twitched slightly and he simply said, "That's assuming the two incidents are directly related."

Lindsay was puzzled. "But of course they are. You can't seriously expect anyone to believe that there are two homicidal maniacs running around out there? Deborah was connected to Crabtree while he was alive; in my book, that makes a strong case for a connection when they're both involved in murderous attacks in the same place within days of each other."

"The attack on Deborah Patterson could have been a random attack on one of the peace women by someone who's got a grudge against the camp," he argued mildly.

Lindsay shook her head. "No way. If anyone was going to do that, they'd pick a spot much nearer the road, where they could make a quick getaway. The woods are really dense around where Debs was attacked. That was someone watching and waiting and biding his time, someone who knows enough about the way things work round here to know where to keep his eyes open."

Rigano smiled. He almost seemed to be enjoying their sparring. "All right," he conceded. "I'll grant you the assumption for now that the incidents were connected. Where do we go from there?"

"Do you want the hypothesis or the evidence?"

"I'll have the evidence, then you can give me the theory."

"Item one. A cassette tape. It was among Rupert Crabtree's papers in the RABD files. It's not what it says on the label - it's a recording of signals traffic on computer that would be of interest both to this country's allies and our enemies." She put the tape on his desk. He picked it up, studied it, and put it down again. He nodded encouragingly.

"Item two. Debs thinks she's being haunted by the ghost of Rupert Crabtree. She thinks she saw him walking the dog after he was dead, and she's convinced it was Crabtree who attacked her.

"Item three. There is someone around, the guy you called Mr. Stone, who is taking an interest in what's going on. He's not CID. You tell me he's not SB. That means, given the contents of this tape, that he's MI5 or 6. I imagine from what little I know about intelligence that he's MI6 K Branch. They're the ones who keep track of Soviet and satellite state agents, aren't they?"

A trace of the lighter side of his personality flickered across Rigano's face as he smiled and said, "You seem to know what you're talking about."

Lindsay immediately bristled. She was determined not to grant him any rights where she was concerned. "Please don't patronize me. I'm not a little woman who needs patting on the head because she can play the big boys' game."

The shutters came down over his eyes again. "That wasn't my intention," he replied coolly. "Is that the extent of your evidence?"

"There's one more thing. But it's conjecture rather than hard fact. What if Rupert Crabtree's gun was being carried not for defense but for attack?"

For the first time, Rigano looked truly alert, as if she was telling him something he did not know, or something he did not want her to know. "Why should he?" he demanded.

"If I can explain my idea about what really happened, you'll see why he should," Lindsay replied. "Are you prepared to hear me out?"

He glanced at his watch. It was almost half past five. "I've got half an hour," he said. "Will it take longer that that?"

Lindsay shook her head. "It's not a long story. It's not a very edifying one either. Treachery and greed, that's what we're into here, Jack." He nodded and sat back, attentive.

"Simon Crabtree is a computer prodigy. He's one of those people who reads a program like you or I read a page in the newspaper. And he's a hacker. Even when he was at school, they commented on his rare skill at busting into other people's private programs. No one had any doubt that he should be looking at a future in computers. No one, that is, except his father, who was conservative enough to be determined that his only son should be properly qualified in something. So he refused to help Simon set up his software business.

"I've seen inside that lock-up, and, while I don't know too much about computers, I'd say that the equipment in there must run into several thousands of pounds, easily. Maybe even five figures. Now, he wouldn't have got that kind of money from a bank, so where did it come from?

"It's my belief that it came from a foreign power. Almost inevitably the Soviets or an East European Soviet satellite. That cassette you've got there contains a recording of signals traffic from a U.S. military base. I don't know enough about these things to swear that it comes from Brownlow, but the chances are that it does, given that I found it among Rupert Crabtree's papers. What I think happened was this. I think that either Simon was scouted by the Soviets, who learned about his hacking skills and his need for capital, or he approached them with the revelation that he had the key to hack into the base's signals computer. I don't think it's been going on too long, if that's any consolation, because he's only had the business up and running for a few months.

"I'm a bit hazy about what happened to put Rupert Crabtree on to the trail. I'd guess that maybe he saw his son behaving suspiciously or saw him with someone he shouldn't have been with. Either way, he got hold of this tape. I'm still guessing here, but I think he probably did what I did-took it to someone who knows how to crack computer codes and discovered just what I did - that it's top-secret signals traffic. Only, for him, the discovery must have been utterly devastating. Here he is, a pillar of the community, a man in the vanguard of an anti-left-wing campaign, and his son's spying for the Ruskies. Also, to be fair, I think from what I've learned about him that it wouldn't just have been the personal disgrace that would have upset him.

"I think he was a patriotic man who genuinely loved his country. I could never have agreed with his politics, but I don't think he was your stereotype fascist on a power trip. I believe that the discovery of what Simon was doing must have shattered him. And something had really got to him, according to Alexandra Phillips. Are you with me so far?"

Rigano said seriously, "It's a very interesting hypothesis. I think your analysis of Crabtree's character is pretty much on the ball. But do go on. I'm fascinated. You've obviously done a lot of digging that you haven't told me about."

Lindsay smiled. "Isn't that what journalists are supposed to do?"

He frowned. "In theory. But not when they've struck deals with me. Anyway, carry on."

"Crabtree's options, once he had discovered Simon's treason, were fairly limited. He'd realized at once he couldn't ignore it and carry on as if nothing had changed. He couldn't come to your lot because that would completely destroy his life. It would bring his world crashing down about him, and once the press started digging, it would expose all sorts, like his relationship with Alexandra, like RABD's connections with the violent right. It would make it almost impossible for him to go on practising locally. The shame for him and his wife would have been too much, and he was too old to think about starting elsewhere.

"He could have confronted Simon with his knowledge and ordered him to stop, with the blackmail that if he didn't he would go to the authorities. But there's no way that could have been done effectively - Rupert had no way of checking that Simon had really stopped. And Simon probably knew his father well enough to realize that he wouldn't have carried through his bluff. So there would have been a stalemate. And it wouldn't have taken much imagination on Crabtree's part to work out what his fate would probably be, once Simon reported back to his control that his father knew he was spying.

"The only other option was to dispose of the son whose treachery was putting his family and his country at risk."

Rigano picked up a pencil and started doodling on a sheet of paper by his phone. He looked up. "Tell me more," he said.

"Not much more to tell, is there? Crabtree had a gun. He was licensed for it. He knew how to shoot. But I'd guess that he probably didn't intend to use it unless he had to. He'd have tried to divert suspicion to the peace women, so he'd likely have used the gun as a threat and then killed Simon some other way. He arranged to meet Simon on the common to have a private talk. When he pulled the gun, Simon panicked and overpowered him. Then, realizing there was nothing else for it, he killed him.

"Then that cool young man went home, bringing the bemused and terrified family dog, which of course explains why the dog was on the doorstep and not howling over the corpse of his master as one would expect. Then Simon stripped off his muddy bike leathers and put up a good show for when the police arrived. That, by the way, is when Deborah saw him. You must have noticed that he's physically, if not facially, very like his father. Deborah knew Crabtree but not Simon, and she thought it was the father and not the son she saw outlined against the night sky. It was only much later that she realized he must already have been dead by then.

"And appallingly, it was I who tipped Simon off that Deborah had seen him. I said she'd seen his father, but he was quicker to the point than me and immediately knew who Deborah had really got a glimpse of. He understood the significance and decided Deborah was too high a risk to leave unattended. Hence the attack on her, and hence her conviction that Rupert Crabtree was haunting her. She must have caught a brief, peripheral glimpse of Simon and subconsciously identified him wrongly. I hope you've still got a guard on her."

Rigano put his pencil down and sighed. "Very plausible," he muttered. "Fits all the facts in your possession."

"It's the only theory that does," Lindsay replied sharply. "Anything else relies on a string of completely implausible coincidences."

"I tend to agree with you," he replied in an offhand way.

"So what are you going to do about it? You've got the evidence there," Lindsay said, pointing at the tape. "You can get your forensic people to examine the clothes Simon was wearing that night. There must be traces."

"I'm going to do precisely nothing about it, except to say, well done, Lindsay. Now forget it," he said coldly.

Lindsay looked at him in stunned amazement. "What?" she demanded, outraged. "How can you ignore what I've just told you? How can you ignore the evidence I've given you? You've got to bring him in for questioning, at least!"

He shook his head. "No," he said. "Don't you understand?"

"No, I bloody don't," she protested bitterly. "You're a policeman. You're supposed to solve crimes, arrest the culprits, bring them to trial. You're quick enough to do people for speeding - suddenly murder is a no-go area?"

"This murder is," he replied. "Why else do you think a uniform is in charge instead of the CID? Why else am I working with two men, a dog and a national newspaper hack? I am supposed to fail."

Lindsay was dumbstruck. It didn't make any sense to her. "I... I don't get it," she stuttered.

Rigano sighed deeply. He spoke quietly but firmly. "I shouldn't tell you this, but I feel I owe it to you after the way you've worked through this. Simon Crabtree is part of a much bigger operation that's out of my hands and way over my head. I am not allowed to touch him. If he ran amok in Fordham High Street with a Kalashnikov, I'd have a job arresting him. Now do you understand?"

Lindsay's fury suddenly erupted. "Oh yes, I bloody understand all right. Some bunch of adolescent spymasters think they can get to some tuppenny-ha'penny KGB thug via Simon Crabtree. So it's hands off Simon. And that means it's open season on Deborah. She can't be kept under police guard forever. Simon doesn't know he's sacrosanct. He'll have another go. And next time, Deborah might not be so lucky. You expect me to stand by while an innocent woman is put at risk from that homicidal traitor? Forget it!"

"So what are you going to do about it?"

"I'm a journalist, Jack," she replied angrily. "I'm going to write the story. The whole bloody, dirty story." She got to her feet and made for the door. As she opened it, she said, "But first of all, I'm going to talk to Simon Crabtree."