He blinked, surprised. 'It belongs to the hotel. Once or twice a day somebody clears it and just posts the letters in the nearest proper box.'

That sounded like Castle's service with style, all right. 'Open it up.'

Now he really did look surprised. 'I think there is nothing in there…'

'So we'll check.'

He found the key on the big bunch and lifted the sloping lid. 'No, nothing.'

I looked for myself. 'All right, hand it over.'

'What?' The surprise was still there, but maybe a little fear behind it.

'The letter the Professor wrote. Hand itover! '

'But what letter?'

That's why he put on a shirt. To come downstairs. And he bought the stamps off you and paid with a new 250-mil. note and it was too late for anybody to post it tonight' but not too late for a fat vulture like you to remember it once the bloke was dead. I'll bet you'd have sorted out his room, too, if that chambermaid hadn't been there. Now either give it to me or stick around until I've got back Lazaros and told him my theory.'

'It is in my room,' he said shakily.

I jerked my head at the stairs.

He brought it down inside a couple of minutes: an ordinary long pale blue airmail envelope with a handwritten address to Pierre Aziz in Beit Mery, Beirut, Lebanon.

'I was going to post it in the morning,' Papa said, trying hard to get a little dignity back into his voice.

The envelope was still sealed so he might have been telling the truth except I was quite sure he wasn't. From its thickness, it probably only held one folded piece of paper. I stuck it in my shirt pocket.

'What are going to do?' he asked.

'Sleep on it. Behind a locked door.'

His expression got suddenly crafty. 'Now why should I not tell the Inspector that you have it?'

'Because you'd still involve yourself. And because, when the going gets rough, you scare easier than I do.'

After that, I knew our relationship would never be the same again. But then, it already wasn't.

Breakfast ran long and late the next morning. I got down around ten and Kapotas was already having his first coronary of the day over the desk cash box.

'They steal everything! ' he wailed. 'Even a few-'

'Don't worry, that was me. I'll pay you back when you pay me.'

'I keep saying that I am not responsible for-'

'It's only money. And not even ours.' I ducked into the dining-room.

Ken was the only one I knew there; no Mitzi, no Suzie and there'd been no sign of Sergeant Papa. I sat down with Ken and ordered three poached eggs and enough coffee to swim in, then started on the last of Ken's coffee to bridge the gap. A half hangover, not the sort where you've got broken glass in your veins, always gives me an appetite like an opera singer.

Ken wasn't looking so hopeful of the day. His eyes were puffy and red – youdo lose your alcohol capacity – and he was morosely scratching a new pattern in an old gravy-stain on the cloth.

'What's the matter?' I asked. 'Wasn't it like it is in the women's magazines? You're just getting old. Lucky to be able to-'

'Ah, shut up. I got my wick trimmed all right. It's Bruno.'

'You really liked him?'

'He was a pretty nice bloke, though the competition wasn't high, in there. I just don't see why… and cancer patients just don't kill themselves, anyway. Once you know you've only got so long to live, it seems too sweet to waste. Have you ever heard of anybody committing suicide in the condemned cell?'

'Yes: Hermann Goring.'

'For God's sake… he doesn't count. Anyway, he only beat the rope by a few hours, didn't he?'

'And he was a pilot.' I don't know why I was sounding so cheerful about it, except that it was too early to feel suicidal myself. Then my eggs arrived and I got noshed into them for a minute or two. 'Anyway,' I said finally, 'he wrote a letter last night. Posted it in the box in the hall and Sergeant Papa nicked it and I nicked it off him.'

Ken was staring at me with more than the puffiness narrowing his eyes. 'Who to? What's it say?'

'Bloke in Beirut. And I haven't opened it.' I nudged my jacket with my knife handle and the letter crackled in my pocket.

'Keep your voice down,' Ken said quietly. 'The bloke at the next table's a plainclothes jack.'

I didn't ask how he knew, just waited for a reasonable excuse to glance sideways. A nice clean-cut thirty-year-old in a fresh white shirt and not a hotel guest unless he'd come aboard this morning. Well, it figured. If I'd been Lazaros I'd have sent somebody around to drink a few cups of coffee and keep his ears wide open. The Inspector might not think there was something behind the Professor's death, but he'd be quite sure there was something behind the Professor.

I said gently: 'It could just be the suicide note the Inspector wanted him to have left. I suppose there's no law about posting one instead of sticking it on the mantelpiece.'

'To somebody in Beirut? When his own daughter's next door?'

'Are you looking for logical behaviour in a suicide?' I finished my last egg. 'I suppose it'd be more proper for Mitzi to read it than for Lazaros, and he'd certainly open it, but then again – if it is a suicide note, it might cause her unnecessary grief, right?'

'You're achieving new standards in logical hypocrisy.' He poured himself some of my coffee. 'So what now?'

'We wait until we're alone, Josephine.'

He half grinned. The puffiness was fading and his face was taking on the old lean, shrewd alertness. He nodded briefly and leant back in the chair. 'What happened to that girl at the Gat-wick pub…'

It took five minutes before the cop decided he couldn't go on reading his future in the bottom of the little coffee-cup and wandered out. I twitched my chair to get my back to the glass doors and slid the envelope across the table.

Ken shook his head, barely a quiver. 'Pierre Aziz? Don't know him.'

'Nor me, though maybe I've heard something… Anyway, Beit Mery's no refugee camp.'

'It's that hill with the fancy great hotel, isn't it? The Al Boustan.'

'That's the place.' I worked one fingertip in under the envelope flap. 'Well, jog my elbow.'

He grinned, reached and bumped my aim. The envelope ripped open. 'Dear me, it seems to have come undone…' I unfolded the single piece of good-quality ten-by-eight writing paper with the single line Professor Doktor Bruno Spohr engraved across the top. No address; a professional travelling man. And underneath… a big slab of type-written German, ending in two signatures, one of them Spohr's. I don't read German much beyond'Bier' and'Flugplatz' and I was pretty sure Ken still didn't either. The sheet had a slightly lop-eared, worn look; certainly older than last night. I shrugged and passed it across.

Ken frowned down at it. 'Oh Christ, why didn't we think of a German speaker writing in German… Das Schwert das wir in der Gruftin Akkaentdeckt haben… Ohhell. Akka must be Acre, but what'sa Schwert anda Gruft?'

'Dunno. What's the other signature?'

'Franz Meisler.The Prof's assistant, maybe, it's dated eighteen months ago; before Bruno got pinched.' He skimmed down the rest of the text. 'There's some dimension in here, too… what does 1003 millimetres sound like?'

'Like just over three feet. Maybe it's a treasure map in words: one metre north-west of the lonesome pine…'

'Well, a suicide note it ain't. And we'll have to show it to Mitzi. How do we explain how it got opened?'

'We blame the Sergeant, of course.'

'Stupid of me.' He held it up. 'You or me?'

'You know the lady best.'