As some safeguard against this possibility, he clapped on his bowler.

‘Not unless somebody opens the cabinet for the 12.30 gramophone orgy… For God’s sake, padre, stand away from that lid!’

The vicar, who had advanced towards the cabinet, started away guiltily at the peremptory tone.

‘I was only looking more closely at the string,’ he explained. ‘You can’t see it at all against the panelling, you know. Most remarkable. It’s being so black and so fine, I suppose.’

‘That.’ said Peter, ‘is the idea of fishing-line. I’m sorry I shouted, but do keep back in case of accident. Do you realise you’re the one person in this room who isn’t safe?’

The vicar retired into a corner to work this out. The door was flung open, and Mrs Ruddle, uncalled and unwanted, announced in loud tones:

‘’Ere’s the p’leece!’

‘There!’ said Mr Puffett. He tried to urge her out, but Mrs Ruddle was determined to know what all this long conference was about. She planted herself firmly beside the door with arms akimbo.

Kirk’s ox-like eyes went to Peter and then followed his glance up to the ceiling, where they encountered the astonishing phenomenon of the cactus, floating Houdini-fashion, without visible means of support.

‘Yes,’ said Peter. “That’s where it is. But don’t touch that cabinet, or I won’t answer for the consequences. I fancy that’s where that cactus was at 9.5 p.m. last Wednesday week, and that’s why Sellon was able to see the clock. This is what’s called reconstructing the crime.’

“The crime, eh?’ said Kirk.

‘You wanted a blunt instrument that could strike a tall man from behind and above. There it is. That would break the skull of an ox-with the power we’ve put behind it.’

Kirk looked at the pot again. ‘H’m,’ he said slowly. ‘Pretty-but I’d like a bit o’ proof. There weren’t no blood nor ’air on that there pot w’en last see it.’

‘Of course not!’ cried Harriet. ‘It was wiped.’

‘When and how?’ said Peter, slewing round on her sharply.

‘Why, not till last Wednesday morning. The day before yesterday. You reminded us only just now. On Wednesday morning, under our very eyes, while we all sat round and watched. That’s How, Peter, that’s How!’

‘Yes,’ he said, smiling at her excitement. ‘That’s How. And now we know How, we know Who.’

‘Thank God, we know something at last,’ said Harriet. At the moment she cared little for How or Who. Her jubilee was for the alert cock of Peter’s head, as he stood and smiled at her, balancing himself lightly and swaying a little on his toes. A job finished-and, after all, no failure-no more frustrated dreams about chained and defeated men seeking a lost memory among hot deserts horrid with prickly cactus.

But the vicar, not being Peter’s wife, took the thing otherwise.

‘You mean,’ he said, in a shocked voice, ‘that when Frank Crutchley watered the cactus and wiped the pot-oh! but that is a dreadful conclusion to come to! Frank Crutchley one of my own choirmen!’

Kirk was better satisfied.

‘Crutchley?’ said he. ‘Ah! now we’re getting at it. He had his grudge about the forty pound-and ’e thought he’d get even with the old man and marry the heiress-two birds with one blunt instrument, eh?’

‘The heiress?’ exclaimed the vicar, in fresh bewilderment. ‘But he’s marrying Polly Mason-he came round about the banns this morning.’

‘That’s rather a sad story, Mr Goodacre,’ said Harriet. ‘He was secretly engaged to Miss Twitterton and he-hush!’

‘D’you think they were in it together?’ began Kirk-and then suddenly woke up to the fact that Miss Twitterton was in the room with them.

‘I couldn’t find your fountain-pen anywhere,’ said Miss Twitterton, earnest and apologetic. ‘I do hope-’ She became aware of something odd and strained in the atmosphere, and of Joe Sellon, who was stupidly gaping in the one direction that everybody else was avoiding.

‘Good gracious!’ said Miss Twitterton. ‘What an extraordinary thing! How ever did Uncle’s cactus get up there?’

She made a bee-line for the cabinet. Peter caught her and pulled her back.

‘I don’t think so,’ he said, cryptically, to Kirk over his shoulder; and led Miss Twitterton away to where the vicar still stood petrified with astonishment.

‘Now,’ said Kirk, ‘let’s get this clear. How exactly do you make out he worked it?’

‘If that trap was set like that on the night of the murder when Crutchley left at 6.20,’ (Miss Twitterton uttered a faint squeak) ‘then, when Noakes came in, as he always did at half-past nine, to turn on the wireless for the news-bulletin-’

‘Which he did,’ said Mrs Ruddle, ‘reg’lar as clockwork-’

‘Why then-’

But Harriet had thought of an objection, and whatever Peter thought of her she must put it.

‘But Peter-could anybody-even by candlelight walk a right up to that cabinet without noticing that the cactus wasn’t there?’

‘I think-’ said Peter.

The door opened so quickly that it caught Mrs Ruddle sharply on the elbow-and Crutchley walked in. In one hand he carried the standard lamp, and had, apparently, come in to fetch something on his way to the van outside, for he called back to some invisible person behind him.

All right-I’ll get it and lock it up for you.’

He was abreast of the cabinet before Peter could say:

‘What do you want, Crutchley?’

His tone made Crutchley turn his head.

‘Key o’ the radio, my lord,’ he said briefly and, still looking at Peter, lifted the lid.

For the millionth part of a second, the world stood still. Then the heavy pot threshed down like a flail. It flashed as it came. It skimmed within an inch over Crutchley’s head, striking white terror into his face with its passing, and shattered the globe of the lamp into a thousand tinkling fragments.

Then, and only then, Harriet realised that they had all cried out, and she among them. And, after that, there was silence for several seconds, while the great pendulum swung over them in a gleaming arc.

Peter spoke, warningly:

‘Stand back, padre.’

His voice broke the tension. Crutchley turned on him with a face like the face of a beast

‘You devil! You damned cunning devil! How did you know? Curse you-how did you know I done it? I’ll have the throat out of you!’

He leapt, and Harriet saw Peter brace himself; but Kirk and Sellon caught him as he sprang from under the death-swing of the pot. He wrestled with them, panting and snarling.

‘Let me go, blast you! Let me get at him! So you set a trap for me, did you? Well, I killed him. The old brute cheated me. So did you, Aggie Twitterton, blast you! I been done out o’ my rights. I killed him, I tell you, and all for nothing.’

Bunter went quietly up, caught the pot as it swung and brought it to a standstill.

Kirk was saying:

‘Frank Crutchley, I arrest you…’

The rest of the words were lost in the prisoner’s frenzied shouting. Harriet went over and stood by the window. Peter had not moved. He left Bunter and Puffett to help the police. Even with this assistance, they had their work cut out to drag Crutchley from the room.

‘Dear me!’ said Mr Goodacre. “This is a most shocking thing!’ He picked up his surplice and stole.

‘Keep him off!’ shrieked Miss Twitterton, as the struggling group surged past her. ‘How horrible! Keep him off! To think that I ever let him come near me!’ Her small face was distorted with fury. She ran after them, shaking her clenched fists and crying out grotesquely: ‘Beast! beast! how can you kill poor Uncle!’

The vicar turned to Harriet.

‘Forgive me. Lady Peter. My duty is with that unhappy young man.’

She nodded, and he followed the rest out of the room. Mrs Ruddle, arrested on her way to the door by the sight of the fishing-line dangling from the pot, was illuminated with sudden understanding.

‘Why, there!’ she cried, triumphantly. “That’s a funny thing, that is. That’s the way it was when I come in ’ere Wednesday morning to clear for the sweep. I took it off meself and throwed it down on the floor.’