Lindsay cursed the one-way system that had turned a city she knew like the back of her hand into a convoluted maze. Wryly she remembered the April Fool's Day joke that had been played by a bunch of math students when she'd been an undergraduate. They'd worked out that if they reversed just one sign in the traffic system, vehicles would be able to enter but not to leave it. The city had ground to an infuriated, hooting halt by eight in the morning, a problem it had taken the traffic experts till noon to solve. The memory kept Lindsay mildly amused until she finally pulled into the car park at the Computer Sciences Laboratory at eleven. She had stopped only to plead with Duncan for a day off, a request he reluctantly granted after she had delivered a short, first-person piece about her visit to the hospital. Since the Clarion had changed the front page to accommodate her story from the night before, the pugnacious news editor was determined to milk their exclusive line for all it was worth. Lindsay had deliberately left out all references to ghosts and stressed Deborah's ignorance of her attacker's identity. Then, with great satisfaction, she switched off her radio pager for the day.

"Lindsay!" exclaimed Annie as she emerged into the reception area looking more like an earth mother than a computer scientist, dressed as she was in a Laura Ashley print. "I thought you were going to phone." She escorted Lindsay through the security doors and down an air-conditioned corridor.

"Sorry," said Lindsay. "It's just that... well, I needed to be doing something and I can't get any further till I know what's on that tape."

Annie stopped in her tracks and studied her friend carefully. "What's happened, Lindsay? You look completely out of it. Getting involved with murders doesn't seem to agree with you."

Lindsay sighed. "Can we sit down somewhere? I don't even know where to begin." Annie ushered Lindsay into her office, a tiny cubby hole with a remote terminal dominating it. Lindsay slumped into a low, easy chair while Annie sat at her desk. Lindsay lit a cigarette then stubbed it out almost immediately, remembering that it was forbidden in the computer areas.

"Last night, somebody tried to kill Deborah and nearly succeeded. It was me who found her. I thought... I thought she was going to die. It was terrible, Annie. Made me realise... I don't know... how dangerous all of this is. Unless someone equally screwy is out to avenge Crabtree's death, it's got to be Crabtree's murderer. But it's too much a coincidence to believe there are two different killers on the loose. And that means, as far as I'm concerned, that it's a race against time to prove who really did it before he has another go and succeeds." Annie nodded encouragingly.

"I thought I could rely on the police to get their fingers out," Lindsay went on. "But I don't know, it all seems very strange to me. For some reason it's a uniformed copper who's running the show, not the CID, and there's some guy who's always around who's either Special Branch or something odd. And somehow there doesn't seem to be any urgency about what's going on. This cop, Rigano, seems dead straight, but even he's not getting the action going. To begin with, he was keen enough to enlist my help and stay abreast of what I was up to. But now, it's almost as if he doesn't want me to get any closer to the truth.

"I think I'm beginning to have just an inkling of an idea about who did it, but I haven't a clue why. I think the answer, or part of it, is that tape."

Annie grimaced. "Well, add that to the murderer's assumption that Debs will have told you all she knows, and you could be the next target. And knowing you, I suppose all this is upfront in the Daily Clarion?"

"Sort of. I mean, I've done a couple of exclusives."

Annie thought for a moment. "And?" she prompted.

"And what? Isn't that enough? That I could be next on a killer's hit list?"

"I know you. There's something else. Something personal."

Lindsay gave a tired smile. "I'd forgotten how sharp you can be," she said. "Yes, there is something more. But it seems hellish trivial beside the real problems of people getting hurt and killed. I'm having a difficult time with Cordelia just now. She seems jealous of the time I spend at the camp, especially now Debs is there."

"Hmm," Annie murmured. "She does have a point, though, doesn't she?"

Lindsay looked astonished. "I didn't - "

"You didn't have to, lovey. It's not what you say, Lindsay, it's how you say it. 'Twas ever thus with you. And if it's that obvious to me, who hasn't seen you for months, then it must stick out like a sore thumb to Cordelia. She must be feeling very threatened. If I were you, I'd make a point of going home tonight, no matter what other calls you think there are on your time."

Lindsay smiled. "I'd love to do just that. But a lot depends on what you've got to tell me about that tape. I'm convinced that that's where the answers lie."

Annie frowned. "I hope not," she said. She unlocked her desk and took out a pile of print-out paper and the tape. "I'm sorry to disappoint you," she said. "I don't think you'll find many answers here."

"You mean you haven't been able to crack it?" Lindsay asked, her voice full of disappointment.

"Oh no, it's not that," said Annie cheerfully. "I won't bore you with the details, but I must thank you for a really challenging task. It took me a lot longer that I thought. I didn't get to bed till three, you know, I was so caught up in this. Whoever constructed that programme knew exactly what he was doing. But it was one of those thorny problems that I can't bear to give up till I've solved it.

"So I stuck with it. And this is what I came up with." She handed Lindsay a sheaf of print-outs, consisting of pages of letters and numbers in groups.

"Is this it?" asked Lindsay. "I'm sorry, it's completely meaningless to me. What does it represent?"

"That's what I don't know for sure," Annie admitted. "It may be some encoded information, or that in itself could be the information. But unless you know what it is you're looking for, it doesn't take you any further forward in itself. I've never seen anything quite like it, if that's any help."

Lindsay shook her head. "I hoped that this would solve everything. I think I was looking for a motive for murder. But I seem to have ended up with another complication. Annie, do you know anybody who might be able to explain this print-out?"

Annie picked up her own copy of the printed message and studied it again. "It's not my field, and I'm not sure whose it is until I know what it is, if you see what I mean." She sighed. "The only thing that occurs to me, and it's the vaguest echo from a seminar I went to months ago, is that it might possibly be some kind of signals traffic. I don't know for sure, and I can't even put my finger on why I believe that. But that's all I can go on. And I can't put you in touch with anyone who might help because, if it is signals intelligence, then the ninety-nine per cent probability is that it's Official Secrets Act stuff. I'm bound by that, and so is anyone else who might help. And if I put you in touch, they'll have to report the contact in both directions. Just what have you got yourself into this time, Lindsay?"

Lindsay sighed again. "Deep waters, Annie."

"You should be talking to the police about this."

"I can't, not yet. I don't trust what's going on, I told you."

"Where did this come from, Lindsay? For my own protection, I think you need to tell me a bit more about the provenance of this tape. It all looks extremely dodgy to me."

"I found it in a collection of papers belonging to Rupert Crabtree, the man who was murdered. His son owns a small software house in Fordham. It was in such a strange place, I figured it might be significant. And now, from what you tell me, it could be more than just a clue in a murder mystery. Have you made a copy of the tape?"

Annie nodded. "I always do, as a precaution."

"Then I'd suggest you disguise it as Beethoven string quartets or something and hide it in your tape collection. I'd like there to be a spare, in case anything happens to my copy. Or to me."

Annie's eyebrows rose. "A little over the top, surely?"

Lindsay smiled. "I hope so."

"You can make a copy yourself on a decent tape-to-tape hi-fi, you know," Annie remarked in an offhand way. "And you will be going home tonight, won't you?"

Lindsay grinned. "Yes, Annie, I'll be going home. But I've got a couple of things to do first." She stood up. "Thanks for all your work. Soon as all of this is over, we'll have a night out on me, I promise."

"Let's hope those aren't famous last words. Be careful, Lindsay, if this is what I think it might be, it's not kid's stuff you're into." Suddenly she stood up and embraced Lindsay. "Watch your back," she cautioned, as the journalist detached herself and made for the door.

Lindsay turned and winked solemnly at Annie. "Just you watch me," she said.

As she wrestled with the twin horrors of the one-way system and the pay phones of Oxford, Lindsay decided that she was going to invest in a mobile phone, whatever the cost. In frustration, she headed out towards the motorway and finally found a working box in Headington. Once installed, she flipped through her contacts book until she found the number of Socialism Today, a small radical monthly magazine where Dick McAndrew worked.

She dialed the number and waited to be connected. Dick was a crony from the Glasgow Labour Party who had made his name as a radical journalist a few years earlier with an expose of the genetic damage sustained by the descendants of British Army veterans of the 1950s atom bomb tests. He was a tenacious Glaswegian whose image as a bewildered ex-boxer hid a sharp brain and a dogged appetite for the truth. Lindsay knew he'd recently become deeply interested in the intelligence community and GCHQ at Cheltenham. If this was a record of signals traffic, he'd know.

Her luck was still with her. Dick was at his desk, and she arranged to meet him for lunch in a little pub in Clerkenwell. That gave her just enough time to go home and swap her bag of dirty washing for a selection of clean clothes. She made good time on the motorway, which compensated for the time she lost in heavy West London traffic. Being behind the wheel of her MG relaxed her, and in spite of the congested streets, she was almost sorry when she turned off by Highbury Fields and parked outside the house.

She checked her watch as she walked through the front door and decided to make time for herself for a change. She stripped off and dived into a blessedly hot shower. Emerging, she carefully chose a crisp cotton shirt and a pair of lined woollen trousers still in the dry cleaners' bag. She dressed quickly, finishing the outfit off with an elderly Harris Tweed jacket she'd liberated from her father's wardrobe. In the kitchen, Lindsay scrawled a note on the memo board: "12:45. Thurs. I intend to be back by eight tonight. If emergency crops up, I'll leave a message on the machine. Love you."

She pulled on a pair of soft grey moccasins, light relief after her boots, and ran downstairs to the street. There she picked up a passing cab which deposited her outside the pub. She shouldered her way through the lunchtime crowds till she found Dick sitting in a corner staring morosely at a pint of Guinness. "You're late," he accused her.

"Only ten minutes, for Chrissake," she protested.

"It's the job," he replied testily. "You get paranoid. What you drinking?" In spite of Lindsay's attempts to buy the drinks, he was adamant that he should pay, and equally adamant that she had to have a pint. "I'm no' buying bloody half pints for an operator as sharp as you," he explained. "If I'm on pints, so are you. That way I'm less likely to get conned."

He returned with the drinks and immediately scrounged a cigarette from Lindsay. "So," he said, "how's tricks? You look dog rough."

"Flattery will get you nowhere, McAndrew. If you must know, I'm in the middle of a murder investigation, my ex-girlfriend is recovering from a homicidal attack, Cordelia's in a huff, and Duncan Morris expects the moon yesterday. Apart from that, life's the berries. Howsabout you?" she snarled.

"Oh well, you know?" He sighed expansively.

"That good, eh?"

"So what have you got for me, Lindsay? What's behind this meet? Must be good or you'd have given me some clue on the phone and chanced the phone-tap guy not being sharp enough to pick it up. Hell mend them."

"It's not so much what I've got for you as what you can do for me."

"I've told you before, Lindsay, I'm not that kind of boy."

"You should be so lucky, Me Andrew. Listen, this is serious. Forget the Simon Dupree of the gay repartee routine. I've got a computer print-out that I'm told might be coded signals traffic. Could you identify it if it was?"

Dick looked alert and intent. "Where d'you get this from, Lindsay?"

"I can't tell you yet, Dick, but I promise you that as soon as it's all sorted, I'll give you chapter and verse."

He shook his head. "You're asking a lot, Lindsay."

"That's why I came to you," she said. "Want to see it?" He nodded and she handed him the print-out. He helped himself to another cigarette and studied the paper. Ten minutes later, he carefully folded it up and stuffed it back in her handbag. "Well?" she asked cautiously.

"I'm not an expert," he said warily, "but I've been looking at intelligence communication leaks for a wee while now. As you well know. And that looks to me like a typical pattern for a US military base. Somewhere like Upper Heyford, Mildenhall."

"Or Brownlow Common?"

"Or Brownlow Common."

"And what does it mean?"

"Oh Christ, Lindsay. I don't know. I'm not a bloody expert in codes. I've got a source who might be able to unscramble it if you want to know that badly. But I'd have thought it was enough for you to know that you're walking around with a print-out of top secret intelligence material in your handbag. Just possessing that would be enough for them to put you away for a long time."

"It's that sensitive?"

"Lindsay, the eastern bloc spend hundreds of thousands of roubles trying to get their hands on material like that. Quite honestly, I don't even want to know where you got that stuff. I want to forget I've ever seen it."

"But if you know what it is, you must have seen other stuff like it."

Dick nodded and took a long draught of his pint. "I've seen similar stuff, yes. But nothing approaching that level of security. There's a system of security codes at the top of each set of groups. And I've never encountered anything with a code rated that high before. It's the difference between the official report in Hansard and what the PM tells herself in the mirror in the morning. You are playing with the big boys, Lindsay." He rose abruptly and went to the bar, returning with two large whiskies.

"I don't drink spirits at lunchtime," she protested.

"You do today," he said. "You want my advice? Go home, burn that print-out, go to bed with Cordelia, forget you ever saw it. That's trouble, Lindsay."

"I thought you were a tough-shit investigative journo, the sort that isn't happy unless you're taking the lid off the Establishment and kicking the Official Secrets Act into touch?"

"It's not like pulling the wings off flies, Lindsay. You don't just do it for the hell of it. You do it when you think there's something nasty in the woodpile. I'm not one of those knee-jerk lefties who publishes every bit of secret material that comes my way, like Little Jack Horner saying, 'See what a good boy am I.' Some things should stay secret; it's when that's abused to protect crime and pettiness and sloppiness and injustice and self-seeking that people like me get stuck in," he replied passionately.

"Okay," she said mildly. "Cut the lecture. But take it from me, Dick, something very nasty has been going on, and I've got to get to the bottom of it before it costs any more lives. If I have to use my terrifying bit of paper to get there, I'll do it. There's nothing wrong with my bottle."

"I never said there was. That's the trouble with you, Lindsay - you don't know when it's sensible to get scared."

By silent consent, they changed the subject and spent half an hour gossiping about mutual friends in the business. Then Lindsay felt she could reasonably make her excuses and leave. She got back to the three-storey house in Highbury at half past two, with no recollection of the journey through North London streets. The answering machine was flashing, but she ignored it and went through to the kitchen to brew a pot of coffee. She had the frustrating feeling that she had all the pieces of the jigsaw but couldn't quite arrange them in a way that made sense. While the coffee dripped through the filter, she decided to call Rigano.

For once, she was put straight through. As soon as she identified herself, he demanded, "Where are you? And what have you been up to?"

Puzzled, she said, "Nothing. I'm at home in London. I visited Deborah this morning and since then I've seen a couple of friends. Why?"

"I want to know what you make of your friend's remark when you saw her in the hospital. My constable thought it might be significant."

"I told him then I didn't understand it," she replied cautiously.

"I know what you told him. I don't believe you," he retorted.

"That's not my problem," she replied huffily.

"It could be," he threatened. "I thought we were co-operating, Lindsay?"

"If I had any proof of who attacked Deborah, do you think I'd be stupid enough to sit on it? I don't want to be the next one with a remodelled skull, Jack."

There was a heavy silence. Then he said in a tired voice, "Got anything for me at all?"

"These bikers who have been terrorising the camp - I think Warminster and Mallard are paying them."

"Have you any evidence of that?"

Briefly, Lindsay outlined what she had learned the day before. "It's worth taking a look at, don't you think? I mean, Warminster and Mallard both wanted Crabtree out of the way. Maybe they used the yobs they'd already primed for the vandalism."

"It's a bit far-fetched, Lindsay," he complained. "But I'll get one of my lads to take a look at it."

Having got that off her chest, Lindsay got to the point of the call. "Has it occurred to you that there might be a political dimension to this situation?"

His voice became cautious in its turn. "You mean that RABD is only a front for something else? That's nonsense."

"I mean real politics, Jack. Superpowers and spies. The person you're looking for didn't really kill for personal reasons; I think we're looking at a wider motive altogether. Somebody doesn't want us to do that. And that's why I think this investigation has got bogged down in trivial details about peace women's alibis."

"That's an interesting point of view, but that sort of thing is all out of my hands. I'm just a simple policeman, Lindsay. Conspiracy theories don't do much for me. I leave all that to the experts. And you'd be well advised to do the same."

Simple policeman, my foot, thought Lindsay. "Is that a warning, Jack?" she asked innocently.

"Not at all, Lindsay. I'm just telling you as simply as I know how that this case isn't about James Bond, it's about savage responses to petty situations. It's about people carrying offensive weapons for mistaken notions of self-defense. Anything else is out of my hands. Do I make myself clear?"

"So who is that blond man who keeps following me? Special Branch? MI5?"

"If you mean Mr. Stone, he's not Special Branch. There's no SB man around here, Lindsay. And no one is following you. I'd know about it if they were. If anyone's being followed, it's not you. You should stop being so paranoid."

Lindsay almost snarled. "Haven't you heard, Jack? Just because you stop being paranoid doesn't mean they're not out to get you."