There wasn't much wrong with Xanthe, I thought. Lonely, worried, only half understanding the adult world, needing reassurance, she longed primarily for exactly what Mercer himself wanted, a friendly united family. She hadn't thought of affronting her parents by cuddling up to a waiter: very much the reverse. She had tried to put me into a difficult position: had been without guile or tricks. I wouldn't have minded having a younger sister like her that I could take places for her to have fun. I hoped she would learn to live in peace with her money, and thought that a month or so of serving other people in a good crew like Emil, Oliver and Cathy would be the best education she could get.

After a while I scanned the whole Chateau and its gardens with the binoculars but I couldn't see Filmer, which wasn't really surprising, and in the end I set off again to walk, and detoured up on to the foot of the glacier, trudging on the cracked, crunchy, grey-brown-green fringe of the frozen river.

Laurentide Ice, one of the passengers had knowledgeably said early on, was the name given to one of the last great polar ice sheets to cover most of Canada twenty thousand years before. Daffodil, nodding, had said her husband had named the horse because he was interested in prehistory, and she was going, to call her next horse Cordilleran Ice, the sheet that had covered the Rockies. Her husband would have been pleased, she said. I could be standing at that moment on prehistoric Cordilleran Ice perhaps, I thought, but if glaciers moved faster than history, perhaps not. Anyway, it gave a certain perspective to the concerns of Julius Apollo.

Back at the Chateau, I went upstairs and drafted a new scene for the script, and I'd barely finished when Zak came knocking to enquire for it. We went into his room where the cast had already gathered for the rehearsal, and I looked round their seven faces and asked if we still had the services of begging Ben, who was missing from the room. No, we didn't, Zak said. He had gone back to Toronto. Did it matter?

'No. not really. He might have been useful as a messenger, but I expect you can pretend a messenger.'

They nodded.

'Right,' Zak said, looking at his watch. 'We're on stage in two and a half hours. What do we do?'

'First,' I said, 'Raoul starts a row with Pierre Raoul is furious to have been discovered to be Angelica's husband, and he says he positively knows Pierre owes thousands in gambling debts which he can't pay. and he knows who he owes it to, and he says that that man is known to beat people up who don't pay.'

Raoul and Pierre nodded. 'I'll put in some detail,' Raoul said. 'I'll say the debts are from illegal racing bets, and I've been told because they were on the Bricknells' horses, OK?'

'OK?' Zak said to me.

'Yes, OK. Then Raoul taunts Pierre that his only chance of getting the money is to marry Donna, and Walter Bricknellsays that if Donna's so stupid as to marry Pierre, he will not give her a penny. He will in no circumstances pay Pierre's debts.'

They all nodded.

'At that point. Mavis Bricknell comes screaming into the cocktail room saying that all her beautiful jewels have been stolen.'

They all literally sat up. Mavis laughed and clapped her hands. 'Who's stolen them?' she said.

'All in good time,' I smiled. 'Raoul accuses Pierre, Pierre accuses Raoul, and they begin to shove each other around, letting all their mutual hatred hang out. Finally Zak steps in, breaks it up, and says they will all go and search both Pierre's room and Raoul's room for the jewels. Zak, Raoul, Pierre and Mavis go off.'

They nodded.

'That leaves,' I said, 'Donna, Walter Bricknell and Giles in the cocktail room. Donna and Walter have another argument about Pierre, Donna stifles a few tears and then Giles comes out of the audience to support Donna and say she's been having a bad experience, and he thinks it's time for a little good feeling all round.'

Giles said, 'OK, good. Here we go.'

'Then,' I said, 'Zak and the others return. They haven't found the jewels. Giles begins to comfort Mavis as well. Mavis says she lived for her collection, she loved every piece. She's distraught. She goes on a bit.'

'Lovely,' Mavis said.

'Walter,' I went on, 'says he can't see any point in jewellery. His jewellery is his horses. He lives for his horses. He says extravagantly that if he couldn't go racing to watch his horses, he'd rather die. He'd kill himself if he couldn't have horses.'

Walter frowned but eagerly nodded. He hadn't had much of a part so far: it would give him a big scene of his own, even if one difficult to make convincing.

'Walter then says Raoul is ruining his pleasure in his horses, and ruining the journey for everyone, and he gives him the formal sack as his trainer. Raoul protests, and says he hasn't deserved to be fired. Walter says Raoul is probably a murderer and a jewel thief and has been cheating him with his horses. Raoul in a rage tries to attack Walter. Zak hauls him off. Zak tells everyone to cool down. He says he will organize a search of everyone's bedrooms to see if the jewels can be found, and he will consult with the hotel's detective and call in the police if necessary. Everyone looks as if they don't want the police. End of scene.'

I waited for their adverse comments and altering suggestions, but there were very few. I handed my outline to Zak who went over it again bit by bit with the actors concerned, and they all started murmuring, making up their own words.

'And what happens tomorrow?' Zak asked finally. 'How do we sort it all out?'

'I haven't written it down yet,' I said.

'But you do have it in mind? Could you write it this evening?'

I nodded twice.

'Right,' he said. 'We'd better all meet here tomorrow after breakfast. We'll have to do a thorough walk through, maybe two or even three, to make sure we get it all right. Tie up the loose ends, that sort of thing. And don't forget, everybody, tomorrow we'll be back in the dining car. Not so much room for fighting and so on, so make it full of action tonight.'

'Tomorrow Pierre gets shot,' I said.

'Oh boy, oh boy,' Pierre said.

'But not fatally. You can go on talking.'

'Better and better.'

'But you'll need some blood.'

'Great,' Pierre said. 'How much?'

'Well…' I laughed. 'I'll let you decide where the bullet goes, and how much gore you think the passengers can stand, but you'd better be to going to live, at the end of it.'

They wanted to know what else I had in store, but I wouldn't tell them: I said they might give the future away by accident if they knew, and they protested they were too professional to do that. But I didn't altogether trust their improvising tongues, and they shrugged and gave way with fair grace.

I watched the walk through which seemed to go pretty well, but it was nothing, Zak assured me afterwards, to the actual live performance among the cocktails.

He came back to my room at eleven, as on the previous night, drinking well-earned whisky exhaustedly.

'Those two, Raoul and Pierre, they really gave it a go,' he said. 'They both learned stage righting and stunts at drama school, you know. They'd worked out the fight beforehand, and it was a humdinger. All over the place. It was a shame to break it up. Half the passengers spilled their cocktails with Raoul and Pierre rolling and slogging on the floor near their feet and we had to give everyone free refills.' He laughed 'Dear Mavis put on the grand tragedy for reporting the theft of the jewels and poured on some tremendous pathos later over losing all her happy memories of the gifts that were bound up in them. Had half the audience in tears. Marvellous. Then Walter did his thing quite well considering he complained to me that no one in their right mind would kill themselves because they couldn't go racing And afterwards, would you believe it, one of the passengers asked me where we got the idea from, about someone killing themselves because they couldn't go racing.'