There was a moment’s blank silence. The night was very still – as still as the night had been when Appleby had sat in Allington’s library, constrained by an excessive hospitality to stop rather longer than he had wanted to. No owls. No frogs. Not a sound.
‘Did I kill Knockdown and Scrape as well?’ Appleby asked. He was wondering whether the madman standing in front of him carried a concealed weapon. Short of that, he could tackle him easily enough.
‘Of course not. Knockdown’s death was a matter of sheer misadventure befalling an intruder. We have established that. Poor Scrape was thrown off his balance by what had happened, and by his exciting afternoon, and by the extravagant notions that had been gaining on him. He simply drowned himself – hitting his head on something as he went down.’
‘So I killed only Martin Allington. It wasn’t your first idea, I’d remind you again. There was that business about spies and international conspiracy. Perhaps that was just to protect me?’
‘Of course. I was determined not to embarrass a guest.’
‘I see.’ Appleby took a long breath. ‘Even although he was a murderer?’
‘You know very well that there is no question of murder. I simply implicated you in a fatal prank. Not even that, indeed. It wasn’t unreasonable that I should show you the son et lumière. It was idle – nothing more than idle – to invite you to have a go.’
‘I remember the words,’ Appleby said.
‘Well, you understand what happened. I knew that you understood what happened, as soon as you said that about twelve o’clock and two o’clock.’ Allington turned and pointed. ‘Swing into this drive in the dark, and you expect to see the lights on the terrace straight ahead of you. Twelve o’clock. Anybody accustomed to arrive by night would have that expectation. But suppose those lights had just gone out, and an almost identical line of lights had sprung up before the castle. Two o’clock. Instinctively, and for a fatal fraction of time, you would steer for that. And it’s what took poor Martin into the lake. Appleby, I repeat that I really do regret it very much. I hate your having the consciousness of such a thing on your hands – utterly innocent though it was.’
‘I’m very much obliged to you.’ Appleby’s tone was grim. ‘I certainly flicked a switch – and the effect was to send the lights on the terrace leap-frogging over the lake and in front of the castle. Would you care to offer any estimate of the length of time they stayed like that?’
‘Oh, quite some time.’
‘I think not. In no time we had the effect of the castle burning. No one would steer a car at that.’
‘It is scarcely material. The coincidence was a dreadful one, in any case. It may have been in the split second that you flicked that switch that Martin swung into the drive.’
‘It was nothing of the sort.’ Appleby got to his feet. During the next few minutes, he judged, he might be safer that way. ‘It was between fifteen and twenty minutes earlier.’
‘You have a freakish streak to you,’ Appleby said, ‘as well as an alarmingly criminal one. You are also a bit of a showman, as you blandly told me yourself. As a practical physicist, of course, you are superannuated. But – and you told me this too – you still get a great deal of fun out of quite small projects. You called the son et lumière “all that rot” – but added that you took an active part in rigging it up. The words are fair enough.’
‘I’m not sure,’ Allington said, ‘that this discussion, my dear Appleby, isn’t taking an injudicious turn.’
‘Perhaps it is. But I don’t recommend too abrupt an end to it.’ Appleby had observed in Allington a disposition to let his right hand hover over a pocket. ‘You can’t accidentally drown me, you know. And anything else wouldn’t be of much use to you. May I go on?’
‘Go on.’
‘You were being steadily blackmailed by your disagreeable nephew. He knew something quite fatal about that scandal you believed you had escaped so successfully. He forced you to make him your heir. I rather think he knew about the treasure, and had extorted his share of that too. It is no doubt the reason why you decided he was to perish where he did – dead on the site of it. The difficulty you faced was that there is no electricity down at this end of the drive. Running a system of hidden wires so far would have been much too risky. But up at the house and castle the situation was quite different. Amid all the litter of the son et lumière, you could do pretty well anything you pleased – and clear away all trace of it again in an hour or so. I don’t know how you made the acquaintance of Knockdown.’
‘Knockdown? What an abrupt transition! Knockdown comes into this fantasy?’
‘You were acquainted with Knockdown. And poor Scrape – unfortunately for him – knew you were. But, for the moment, that is by the way. You enrolled Knockdown as an accomplice, and the rest was perfectly easy. Even sending him to his own death was perfectly easy. When he had, in fact, served your turn, he had your instructions – he was a biddable man, remember, and of low intelligence – to make his way to the gazebo and operate some switch concealed under a bench. It killed him. And you, who were the first to climb up to the place, had only to give him a small shove in order to render him unnoticeable. It was only when you had put me through the business of accidentally killing your nephew – who was, of course, dead already – that you drew attention to him. He had died instantly, and could never give evidence against you.’
There was a long silence. Here and there, the dark surface of the lake threw up the reflection of a star. Beyond, there was a flickering of torchlight as the party which had been searching the castle began to return to the house. Wilfred Osborne must have reached them with the news that all was well.
‘Rasselas,’ Appleby said, ‘is a very well-trained dog.’
Again there was silence. It was followed by a gulping sound, which for a moment Appleby supposed to come from the man standing motionless before him. Then he realized that it came from the lake. Disturbed by Eugene and Digby Lethbridge, the muddy depth was sending up an occasional gassy bubble to explode in air.
‘Timing was the key to the matter,’ Appleby said. ‘I was conscious, in a vague way, of time as behaving queerly. I was being manipulated through it with some very nice calculation. I wasn’t alone in that.’
‘Did you say something about Rasselas?’ Allington asked.
‘Yes.’ Appleby bent down to Eugene and Digby’s small hoard. ‘Here’s the key. Only it isn’t a key. It’s a whistle.’
‘I see the whistle.’ Allington appeared to examine the small object closely. ‘Just a whistle.’
‘The obedient Knockdown, following instructions, threw it into the lake as soon as he’d used it. And then – it was a chance in a thousand – the boys brought it out.’
‘Just why did Knockdown use a whistle?’
‘It was his signal to you that Martin’s car was approaching.’
‘My dear man, you’re crazy. According to your account, we were together in the library as Martin was approaching the drive. We certainly heard no whistle – and nothing else either.’
‘I agree. But Rasselas did. It’s that sort of whistle. You saw Digby blow it a few minutes ago, and we hardly heard a sound. But Rasselas heard it – from as far away as the castle. And he was here in no time.’
‘It was Rasselas who killed my nephew?’
‘That sort of whistle is a man-made equivalent of the squeak of a bat. The pitch is too high to be audible at least to adult human ears, but a dog will hear it, and can be trained to respond to it at once. Nowadays, one sees people using such things regularly in public parks. By the way, you couldn’t stop yourself from looking expectantly at Rasselas from time to time. And then the moment came. Knockdown gave the signal. Rasselas rose and went straight to the door. You pressed a bell – for Enzo, who was no longer in the house. Only it was no longer a bell. It switched off the lights on the terrace, and switched on the lights at the castle. Then, in perhaps five or six minutes, it reversed the process. Easy for you to rig. Easy for you to destroy all traces of – perhaps next morning, perhaps that night. Knockdown was dead – but no policeman was going to cast a vigilant eye on you because of that. By the time Martin’s death was discovered, even the last traces of the son et lumière had vanished. Scrape was the only unexpected complication. And simply because he knew you had lied about Knockdown. He thought things out. But you weren’t going to be blackmailed a second time – not even in the interest of a Cistercian abbey. So you suggested a quiet talk while walking round the lake. Incidentally, you have suggested this quiet talk with me. But, as I’ve said, it won’t do. You can’t drown me. You can only shoot. Well, shoot away – and face Pride’s men afterwards.’
‘Might we perhaps move back to the house?’ Owain Allington had turned away. ‘The others may be wondering what has happened to us.’
‘Yes, we’ll go back.’
‘Perhaps, my dear Appleby, I might stroll ahead. You may want to take a final look round so interesting a spot.’
It was a strange moment – and then Appleby told himself that he was no longer a policeman.
‘Yes, of course,’ he said.
He sat down again on Gate One, and gazed fixedly at the lake. It was a full two minutes before he heard the shot. He rose and walked slowly towards it. The mysterious affair was over.