ate Brannigan's Burglary Tip No. 3: Always burgle offices in daylight hours. People notice lights in offices at night. And people who notice lights in offices that shouldn't be lit up have a nasty habit of being security staff. However, rules are made to be broken, and besides, I wasn't the first unauthorized visitor to Martin Cheetham's office.

That much was obvious from the safe. The reproduction of Monet's Water Lilies that had covered it on my previous visit lay on the floor, while the door of the safe stood ajar. With a frustrated sigh, I took a look inside. I found exactly what I expected. Nothing.

I looked round the room in something approaching despair. There was enough paper in here to keep the least popular detective constable on the force busy for a month. Besides, I wasn't convinced that I would find anything enlightening. I was still pinning my hopes on Cheetham's computer files, particularly since he had the kind of scanner that would have allowed him to import a copy of any document straight into his computer. A quick check of the desk revealed the same absence of discs that I'd noted back at the house. But there was one difference here. The PC sitting on the desk had a hard disc. In other words, the chances were that the master copy of the material on the discs that had been stolen was permanently stored in the machine in front of me.

It was last resort time, so I did the obvious. I switched on the machine. It automatically loaded the system files. Then a prompt appeared, demanding input. I asked the machine to show me the headings under which it was storing stuff. In the following list, I spotted a couple of familiar software names -a word-processing package, a spreadsheet and an accounts program. The rest of the list were probably data files. First, I loaded the word processing package which would allow me to read the data files, then I tried a directory called WORK.C. It seemed to be all the correspondence plus details of deeds on the properties currently being handled. The files were subdivided according to whether Cheetham was acting for vendor or buyer, and what stage he was up to. It was incredibly boring.

The next directory I tried was called WORK.L. When I attempted to access it, nothing happened. I tried again and nothing happened. I tried one or two other ways of getting into the directory, but there was clearly some kind of access block on it. Desperately, I searched Cheetham's drawers again, looking for a single word scribbled somewhere that might be a password for the directory, but without success. I knew that, given time, Bill or I could hack our way into the hidden files of the locked directory, but time was the one thing I wasn't sure I had.

What the hell? I'd taken so many chances already, what was one more? Closing the door on the latch behind me, I left Cheetham's office and returned to the van. I unlocked the security box welded to the floor and took out our office laptop PC. It's a portable machine, more compatible with its desktop equivalents than any married couple I know. It can store the equivalent of sixty novels. I walked back into the Corn Exchange with the fat briefcase, trying hard to look nonchalant, and returned undetected to Cheetham's office by some miracle.

Amongst the resident software on our portable's hard disc was a program that could have been designed for situations like this. It's a special file transfer kit that is used to move data at high speed between portables and desktop machines. I uncoiled the lead that would form the physical link between the two machines and plugged it in at both ends. I switched on my machine and booted up the software.

The program sends over a highly sophisticated communications program, which is then used to 'steal' the files from the target machine. The big advantage of using these kits is that you leave no trace on the machine you've raided. The very process itself also often bypasses any security package that the target PC's operator has installed. The final advantage is that it's extremely fast. Ten minutes after returning to Cheetham's office, I was ready to walk out of the door with the contents of WORK.C and WORK.L firmly ensconced on my own hard disc.

There were just a couple of things I had to do first. I picked up the phone and dialled my favourite Chinese restaurant for a takeaway. Then I called Greater Manchester Police's switchboard. I calmly told the operator who answered that there was a dead body at 27 Tamarind Grove, and hung up.

The traffic had begun to clear, and I picked up my Chinese fifteen minutes later. I'd just parked the van on the drive of my bungalow when I remembered I hadn't checked the tapes from the surveillance. I had two choices. Either I could go indoors and eat my Chinese, preferably with Richard, then, once I'd got all comfy and relaxed, I could schlep all the way over to Stockport and do the business. Or I could go now, and hope that there was nothing that would require my presence there all night. Being what Richard would describe as a boring old fart, I decided to finish the day's work before I settled down. Besides, my bruises were aching, and I knew that if I sank into the comfort of my own sofa, I might never get up again unless it was to crawl into a hot bath.

The drive to Stockport was the Chinese aroma torture. There's nothing worse than the smell of hot and sour soup and salt and pepper ribs when nothing's stayed in your stomach since breakfast and you can't have them. What made it even more frustrating was that there was no one home in my nice little staked-out semi. And, according to my bug, no one had been home either. The phone had rung another couple of times, and that was the sum total of my illegal surveillance.

When I finally got home, the offer of a share in my Chinese distracted Richard from a pirate radio bhangra station he'd been listening to in the course of duty. Sometimes I think his job's even worse than mine. I brought him up to date with my adventures, which added a spice to dinner that even the Chinese had never thought of.

'So he topped himself, then? Or was it one of those sleazy deaths by sexual misadventure?' he asked, doing his impersonation of a tabloid journo as he poked through the char siu pork to get at the bean sprouts below.

'It looks like it. But I don't think he did," I said.

'Why's that, Supersleuth?'

'A collection of little things that individually are insignificant, but taken together make me feel very uneasy,' I replied.

'Want to run it past me? See if it's just your imagination?' Richard offered. I knew he really meant: because you're too well brought up to talk with your mouth full, that means there will be more for me. I gave in gracefully, because he was quite right, I did want to check that my suspicions had some genuine foundation.

'OK,' I said. 'Point one. I take Nell to be Martin Cheetham's girlfriend, judging by the body language on the two occasions I saw them together. She was in the house for about twenty minutes, thirty max, before Lomax arrived. Now if she and Cheetham were getting it on together, that might explain why he was in his drag. But if they were busy having a little loving, what was going down with Lomax and the files?'

'Maybe he just sneaked in and helped himself,' Richard suggested.

'No, he didn't have a key. Someone let him in, but I couldn't see who. I'm convinced Lomax cleared the files out, without Cheetham's co-operation.'

'Why?' Richard asked.

'Because if Cheetham had simply been trying to get incriminating evidence off the premises, he'd only have dumped discs with data on. He wouldn't have ditched the discs with the software programs, because he'd have known enough to realize that a computer with no discs at all is a hell of a lot more suspicious than one with only software and no data,' I explained. Richard nodded in agreement.

'Also, the bedding was clean. It had been changed since the last time the bed had been slept in or bonked on. And there was no bedding in the linen basket or the washing machine or the tumble drier either. So where are the dirty sheets? Now if Cheetham and Nell had been having a cuddle, or whatever it is that transvestite sado-masochists do in bed, there would be forensic traces of her on the bedding. These days, every television viewer knows about things like that. So if she and Lomax had actually killed Cheetham and wanted to make it look like an accidental death during some bizarre sexual fantasy, they'd have to make it look like he'd been alone with his dirty magazine. And that's the only explanation I can find.'

'Maybe he's got a cleaner who comes in and takes his washing home with her,' Richard suggested, sharing his own fantasy.

"Maybe, but I don't think so. The linen basket in the bedroom had dirty clothes in it. Then there's another point about the computers. Whoever cleared out the office safe and took the discs from there, it wasn't Cheetham himself.'

'What makes you say that?' Richard asked. 'I mean, if he was starting to get a bit unnerved by you poking around, wouldn't he try to get rid of anything incriminating?'

'You'd think so. But it was his computer. Whoever did the clearing up of evidence, it was someone who didn't understand that the discs were just the back-up copies of whatever was on the hard disc. They didn't understand about the hard disc, because they left the data on it.'

Richard shook his head. 'I don't know, Brannigan. It's all a bit thin. I mean, ever since you solved Moira's murder back in the spring, you keep seeing suspicious deaths everywhere. Look at the way you got all wound up about that client who died after he changed his will, and it turned out he'd had a heart condition for years, nothing iffy about it.'

'But this is suspicious, even you've got to admit that,' I protested.

'I could give you an explanation that would cover the facts,' Richard said, helping himself to the last of the prawn wontons.

'Go on then,' I challenged, convinced I could unravel any theory his twisted mind could come up with.

Richard swallowed his mouthful, leaned back in his seat and polished his glasses in a parody of the learned academics who pontificate on TV. 'OK. He's had this showdown with you then he's rushed off to meet Lomax. As a result of all this, he's really wound up, but he thinks he's handled it beautifully and he deserves a treat. So he arranges that what's-her-name, the girlfriend, is going to come around for a bit of afternoon delight. Now, from what you've told me about his little treasure trove, who knows what that pair get up to when they're getting their rocks off? Just supposing he's staged this tableau to get her going - he's all done up in his drag and tied up and pretending to hang himself when she arrives. Only it gets out of hand and he snuffs it. OK so far?'

I nodded, reluctantly. Certainly, Cheetham had had enough time alone in the house for that scenario to be feasible. 'OK,' I sighed.

'So what would your reaction be if you arrived at your boyfriend's house to find him hanging dead from the banisters in a frock? Especially if you knew he was into some hooky business that was going to come on top now he's popped his clogs? Remember, for all you know, the lovely lady could be right up to her eyeballs in his little schemes. You'd want to cover your back, wouldn't you?' He gave me that smile of his, the one that got me in this mess in the first place.

'You would indeed,' I conceded.

'So Lomax turns up like a bat out of hell and the pair of them clear out everything that might be remotely connected to Cheetham's little rackets. Lomax takes off with all the incriminating documents and what's-her-name...?' He gave me an inquiring look.

'Nell,' I prompted him.

"Yeah, Little Nell, how could I forget?'

This is no time for obscene rugby songs,' I said.

'Wrong sport, Brannigan. You'll Never Walk Alone is more my speed than The Ball of Kirriemuir. Anyway, as you so correctly pointed out, any fool knows these days that forensic science could place Little Nell not just at the scene of the crime but in the bed if they'd bonked in it since the last time the sheets were changed. She does nothing more than take off the dirty linen so she can wash it in private. Meanwhile, Lomax goes down Cheetham's office and clears out the safe and has it away on his toes with the computer discs in the office. Pick the holes in that." he ended triumphantly.

I thought about it for a moment, then I jumped to my feet. 'Hold everything,' I said on my way through to my spare room, which doubles as study and computer room. I pulled out a book on forensic medicine written for the popular market that Richard had bought me for my birthday as a kind of joke. I ran my finger down the index and turned to the section on body temperature. 'Got it!' I shouted. Richard appeared in the doorway, looking crestfallen. I pointed to the relevant sentence, "The rule of thumb applied by pathologists is that a clothed body will cool in air at between two and five degrees Fahrenheit per hour", it says here,' I said. 'And, when I touched him, he was the same temperature as I was, near as dammit. No way was he between four and ten degrees colder than me, which he should have been if he'd died when you suggested.'

Richard took the book from me and read the relevant section. As usual, the journalist in him took over and he found all sorts of fascinating things he simply had to read about. Leaving him to it, I started to clear up the debris of dinner. I'd just dumped the tinfoil containers in the bin when he reappeared, brandishing the book with a look of pure triumph.

'You should have kept reading,' he said sanctimoniously. That way, you wouldn't have given me half a tale. Look,' he added, pointing to a paragraph on the following page.

"Typically, death by asphyxiation raises the body temperature. This must be taken into account in estimates of the time of death, and is known to have caused confusion in some historical cases,'" I read. 'Bollocks,' I said. 'OK, you win,' I sighed. 'I'm letting my imagination run away with me.'

'So you accept my theory?' Richard asked, a look of total disbelief on his face.

'I guess so,' I admitted.

There's one good thing about it,' he said. 'I mean, I know I've just deprived you of all the excitement of chasing a murderer, but look on the bright side. It puts Alexis in the clear.'

'I never thought for a moment she wasn't in the clear,' I lied frostily.

'Course you didn't,' Richard said, with a broad wink. 'Anyway, now I've saved you all the work of a murder hunt, do I get a reward?'

I checked my body out for bruises and stiffness. I was beginning to heal, no doubt about it. I leaned into Richard's warmth and murmured, 'Your place or mine?'