I had no more dreams that night, but slept heavily and late. It was Geordie who woke me by shaking my shoulder – and incidentally hurting my arm once again. I groaned and turned away, but he persisted until I opened my eyes. 'You're wanted on the phone,' he said. 'It's the Institute.'

I put on my dressing gown and was still thick-headed with sleep when I lifted the receiver. It was young Simms. 'Dr Trevelyan, I've taken over your old office while you're away and you've left something behind. I don't know if it's valuable or if you want it at all.

I mumbled, 'What is it?'

'A manganese nodule.'

I was jolted wide awake. 'Where did you find it?'

'I didn't. One of the cleaners found it under your desk and gave it to me. What should I do with it?'

'Stick tight to it. I'll pick it up this morning. It's got some -relation to work I'm engaged on. Thanks for calling.'

I turned to Geordie. 'All is not lost,' I said, 'we've got a nodule. You dropped some on the floor of my office, remember, and you left one under the desk.'

'I don't see what all the fuss is about. All along you've been insisting that the damn things-are worthless. What's so exciting about this one?'

I said, 'There are too many mysteries connected with this particular lot to suit me. I'm going to take a closer look at this one.'

As I breakfasted on a cigarette and a cup of strong coffee I rang Helen and asked her to read out Mark's death certificate. It was in French, of course, and she had some difficulties over the hand-written parts but we got it sorted out. I put down the phone and said to Geordie, 'Now I want to talk to that doctor as well as Kane.' I felt full of anger and frustration.

'What was the cause of death?'

'Peritonitus following an appendectomy. And that's impossible. The doctor's name is Hans Schouten. It was signed in Tanakabu, in the Tuamotus.'

'He's a hell of a long way from here.'

'But Kane isn't. Do your damndest to find him, Geordie.'

Geordie sighed. 'I'll do my best, but this is a bloody big city, and no one but you and Helen can identify him for sure.'

I dressed and drove down to the Institute, retrieved the nodule from Simms and then went down to the laboratories -I was going to analyse this lump of rock down to the last trace elements. First I photographed it in colour from several angles and took a casting of it in latex – that took care of the external record. Then I cut it in half with a diamond saw. Not entirely unexpectedly, in the centre was the white bone of a shark's tooth, also neatly cut in two.

One of the pieces I put in the rock mill and, while it was being ground to the consistency of fine flour, I polished and etched the flat surface of the other piece. Then the real work began. By early afternoon everything was well under way and luckily I had had the place almost to myself the whole time, but then Jarvis walked in. He was surprised to see me.

'You're supposed to be on leave, Mike. What's all this?'

He looked at the set-up on the bench. I had no worries about that – I could have been analysing anything, and the identifiable half-rock was out of sight. I said lightly, 'Oh, just some homework I promised I'd do when I had the chance.'

He looked at me out of the corner of his eye. 'What have you been up to, young feller? Saw something about you in yesterday's press, didn't I? And I had a chap in from Scotland Yard asking questions about you – and about manganese nodules. And he said you'd killed someone?'

'I had a burglary two nights ago and knocked a chap off the fire escape,' I said. I hadn't seen the papers myself and it hadn't occurred to me that the story would be public. From Simms' lack of reaction, however, it seemed not to be exactly front-page news.

'Um', said Jarvis. 'Very unfortunate. Place is getting like Chicago. Nasty for you. But what's it got to do with nodules?'

'A couple were nicked from my place, with other stuff. I told him they weren't of much value.'

'I made that plain to the Inspector,' growled Jarvis. 'And I take it he's now convinced that your burglars were surprised and took the first things that came to hand. I gave you a reasonable character, by the way.'

I had my doubts about the Yard's acceptance of the front story. The Inspector had struck me as being full of deep suspicions.

'Well, my boy, I'll leave you to it. Anything interesting?' He cast an inquisitive glance at the bench.

I smiled. 'I don't know yet.'

He nodded. 'That's the way it is,' he said rather vaguely and wandered out. I looked at the bench and wondered if I was wasting my time. My own knowledge, backed by that of an expert like Jarvis, told me that this was just an ordinary Pacific nodule and nothing out of the ordinary. Still, I had gone so far, I might as well carry on. I left the glassware to bubble on its own for a while and went to take photomicrographs of the etched surface of the half-nodule.

I was busy for another couple of hours and having to use my bad arm didn't help. Normally I would have used the services of a laboratory technician but this was one job I wanted to do myself. And it was fortunate that I had taken that precaution because what I finally found astounded me. I looked incredulously at the table of figures that was emerging, breathing heavily with excitement and with my mind full of conflicting conjectures.

Then I became even busier, carefully dismantling the glassware and meticulously washing every piece. I wanted no evidence left of what I'd been up to. That done, I phoned the flat.

Geordie answered. 'Where the devil have you been?' he demanded. 'We've had the cops, the press, the insurance people – the lot.'

'Those are the last people I want to be bothered with right now. Is everything clear now?'

'Aye.'

'Good. I don't suppose you found Kane.'

'You suppose rightly. If you're so suspicious of him why don't you take what you've got to the police? They can do a better job of finding him than I can.'

'I don't want to do that right now. I'm coming home, Geordie. I've got something to tell you.'

'Have you eaten, boy?'

I suddenly realized that I hadn't eaten a mouthful all day. I felt very hungry. 'I've been too busy,' I said hopefully.

'I thought so. I'll tell you what; I'll cook up something in this kitchen of yours – one of my slumgullions. Then we won't have to go out and maybe get tagged by one of the newspaper blokes.'

'Thanks. That'll be fine.'

On the way home I bought some newspapers and found that the story had already sunk with no trace. A local shop produced me a copy of the previous day's press and the story was a short one, buried in the body of the paper, lacking in detail and with no mention of what had been stolen, which suited me very well. I didn't want to be questioned on anything concerning manganese nodules. I'm not naturally a good liar.

When I entered the flat I found Geordie busy in the kitchen surrounded by a mouth-watering aroma, and a remarkably well cleaned up living room. I made a mental note never to have glass-fronted bookshelves again – I didn't much like them anyway. Geordie called out, 'It'll be ready in about an hour, so you can get your news off your chest before we eat. I'll be out in two ticks.'

I went to the cabinet for the whisky bottle and two glasses, then picked my old school atlas off the bookshelf. Ink-blotted and politically out-of-date as it was, it would still suit my purpose. I put it on the table and turned to the pages which showed the Pacific.

Geordie came out of the kitchen and I said, 'Sit here. I want to tell you something important.'

He saw the glint of excitement in my eye, smiled and sat down obediently. I poured out two whiskies and said, 'I'm going to give you a little lecture on basic oceanography. I hope you won't be bored.'