The bell sounded loudly. The door opened in the kitchen and footsteps came up the hall. Mrs. Moon appeared in the drawing-room. She looked surprised and rather scared when she saw so many people sitting quietly there.

‘Did you ring, Madam? ’ she asked, and her voice shook a little.

‘I rang,’ said Fatty. He turned to the Inspector. ‘This is the anonymous letter-writer,’ he said. ‘Mrs. Moon!’

Mrs. Hilton gasped. Mr. Goon snorted loudly. All the children drew in their breath sharply. Only the Inspector seemed unperturbed.

Mrs. Moon went pale. She stared at Fatty. ‘What do you mean?’ she said fiercely. ‘How dare you say things like that to a respectable law-abiding woman?’

‘Hardly law-abiding, Mrs. Moon,’ said the Inspector’s stern voice. ‘It is against the law to send spiteful and untrue letters through the post anonymously. But Frederick - please explain. I have enough faith in your intelligence to know that you are making no mistake, if I may say so - but I want to know all about it.’

Mrs. Moon began to cry. ‘Sit down and keep quiet,’ commanded Inspector Jenks.

‘I won’t be treated like this, I won’t!’ wailed Mrs. Moon. ‘An innocent woman like me! Why, I’ve even had one of them awful letters meself!’

‘Yes - you nearly took me in over that,’ said Fatty. ‘I thought that ruled you out - but it was just a bit of artfulness on your part. I see that now.’

‘You bad, wicked boy!’ moaned Mrs. Moon.

‘Silence!’ said the Inspector, in such a fierce voice that Bets jumped. ‘Speak when you’re spoken to, Mrs. Moon, and not unless. If you are innocent you will be given plenty of chance to prove it. We will hear what you have to say when Master Frederick has told his story. Frederick, begin.’

Fatty began, and the other children leaned forward, knowing most of the story well, but longing to hear what the end of it was. Only Fatty knew that.

‘Well, sir, you know already that we worked out that as the letters were posted in Sheepsale each Monday to catch the 11.45 post there, that it was probable the guilty person was some one who took the 10.15 bus from Peterswood to Sheepsale,’ said Fatty.

‘Quite so,’ said the Inspector.

‘Well, we found that none of the bus-passengers last Monday could be the letter-writer,’ said Fatty, ‘and certainly none of them posted a letter. So then we decided to find out if any regular Monday passenger was not on the bus that Monday, and make inquiries about them. And as you know, we found that three regular passengers didn’t travel that day - Miss Tittle, Old Nosey, and Mrs. Moon.’

‘Mr. Goon also worked on the same lines,’ said the Inspector. A sound from Goon made everyone look up.

‘How did you get to see them letters, and see the post-mark?’ demanded Mr. Goon. ‘That’s what I want to know.’

‘Oh, that’s not an important detail,’ said Fatty, anxious not to give away Gladys’s part in that affair. ‘Well, to continue, sir - we found out next that another letter had been sent that Monday - but not from Sheepsale - it had been delivered by hand. So that definitely pointed to somebody in Peterswood, and possibly one of our three Suspects - Old Nosey, Miss Tittle, or Mrs. Moon.’

‘Quite,’ said the Inspector, deeply interested. ‘I must say that your powers of deduction are good, Frederick.’

‘Well, the letter was delivered very early in the morning,’ said Fatty, ‘so I had to find out which of the three Suspects was up early that Tuesday. And I found that all of them were!’

‘Very puzzling,’ said the Inspector. ‘I don’t think Mr. Goon got quite as far as that, did you, Mr. Goon? Go on, Frederick.’

‘That rather shook me,’ said Fatty, ‘and the only thing I could think of next was getting specimens of the handwriting of each of the three - to compare with the printed letters, you see.’

‘A good idea,’ said Inspector Jenks, ‘but surely a little difficult?’

‘Not very,’ said Fatty modestly. ‘You see, I put on a disguise - a red-headed delivery-boy I was.’ There was a snort from Mr. Goon at this.

‘And,’ went on Fatty, ‘I just delivered parcels to all three, and got them to sign receipts in capital letters - so that I could compare them with the capital letters in the anonymous notes!’

‘Most ingenious, if I may say so,’ said the Inspector. He turned to Mr. Goon, whose eyes were bulging at hearing about all this detective work on Fatty’s part. ‘I am sure you agree with me?’ said the Inspector. Mr. Goon did not agree with him at all, but couldn’t very well say so.

‘Well, I found that Nosey couldn’t write at all,’ said Fatty. ‘So that ruled him out. Then I saw that Miss Tittle’s printing, very small and neat and beautiful, wasn’t anything at all like the printing of the letters in the anonymous notes - and that rather ruled her out too - and to my surprise Mrs. Moon’s printing was such a mixture of big and small letters that I couldn’t think she could be the culprit either.’

‘And I’m not!’ said Mrs. Moon, rocking herself to and fro. ‘No, I’m not.’

‘Here’s a specimen of her writing - or rather, printing, sir,’ said Fatty, opening his notebook and showing the Inspector Mrs. Moon’s curious printing, big and small letters mixed. ‘When I asked her about it, she gave me to understand that she couldn’t help it - it appeared to me, sir, that she was muddled in her mind as to which were big and which were small letters.’

‘Quite,’ said Inspector Jenks. ‘So you ruled her out too, as the messages and the addresses on the anonymous letters were apparently printed quite correctly in capitals, with no small letters at all?’

‘Yes, sir,’ said Fatty. ‘And I almost gave up the case. Couldn’t see any light anywhere - and hadn’t got any real clues, either. I didn’t think at the time, either, that Mrs. Moon would write an anonymous letter to herself - though I should have thought of that, of course...’

‘And what about that letter to me? ’ said Mr. Goon, suddenly. ‘That was you, wasn’t it, Master Frederick? Come on, you own up now - that was you, calling me a meddler and a muddler and cheeking me like you always do!’

‘No - I certainly didn’t write you that letter,’ said Fatty. ‘And I think if you compare it with the others, Mr. Goon, you’ll see it’s just like them.’

‘Well, Frederick - how did you come to know in the end that it was Mrs. Moon and nobody else?’ inquired the Inspector.

‘I tell you it wasn’t, it wasn’t,’ moaned Mrs. Moon.

‘That was a sheer bit of luck, sir,’ said Fatty, modestly. ‘Can’t give myself any marks for that! It was Mr. Goon who put me right on the track!’

‘Gah!’ said Mr. Goon disbelievingly.

‘Yes - he suddenly gave us a whole sack of clues - that sack of things on the table!’ said Fatty. ‘And, as soon as I saw them I was able to piece things together and know who had written those disgusting, spiteful letters!’

The Inspector picked up the things one by one and looked at them with interest. ‘Exactly what did these things tell you?’ he said curiously.

‘There’s a dictionary, sir - with Pip’s name in,’ said Fatty. ‘That told me that it probably came from this house and was used by somebody living here. Then I noticed that various words had been looked up for the spelling, and had been underlined - and every one of those words, sir, has been used in the anonymous letters!’

Mr. Goon’s face went redder than ever. To think that boy had got all that out of the things in that sack!

‘The next thing, sir, was the alphabet book,’ said Fatty. ‘And, as I daresay you’ve noticed, the alphabet letters in such a book are always in capitals. A is for Apple, and so on. So I guessed that book had been bought as a kind of reference book for capital letters, by somebody who wasn’t quite sure of the difference in shape of big and small letters. The capital letter G, for instance, is quite different from the small letter g. Naturally the anonymous letter-writer didn’t want to give away the fact that she hadn’t had enough education to know the difference.’

‘Well worked out, Frederick, well worked out,’ said the Inspector, most interested. ‘What about this?’ He held up the copybook.

‘That’s easy, sir,’ said Fatty. ‘Even Bets could read that clue now!’

‘Yes, I can!’ called Bets. ‘That’s a copybook Mrs. Moon must have bought to practise writing capital letters in. There’s lots of capitals printed there in pencil.’

‘I expect if you ask at the stationer’s, Inspector, you’ll find that Mrs. Moon did buy a copybook there some weeks ago!’

‘Make inquiries, Goon,’ said the Inspector. Goon hurriedly made a note in his notebook.

‘The bus time-table was an easy clue,’ said Fatty. ‘I guessed I’d find that 10.15 bus marked. And this bit of torn paper, sir - used as a bookmark in the dictionary, I should think - must have been torn from a recipe of some sort. I knew that as soon as I read the words - “spoonful” - “stir” - “oven”. I expect you will find that they are in Mrs. Moon’s ordinary handwriting, and torn from her kitchen recipe-book.’

‘A most ingenious reading of rather peculiar clues!’ said the Inspector, looking really pleased. ‘What a pity, Mr. Goon, you didn’t take the trouble to look carefully through the clues yourself, and deduct from them all that Frederick has done.’

‘Thought they was all false clues,’ muttered Mr. Goon. ‘Made me angry, they did.’

‘It’s a mistake to let anger cloud your thinking, Goon,’ said the Inspector. ‘If you had only examined these clues carefully, you might have arrived at the same conclusions as Frederick here - but again, you might not!’

It was apparent that the Inspector believed that Goon would certainly not have made such good use of the clues as Fatty had!

Mrs. Moon suddenly threw her apron over her head and wailed loudly. She rocked to and fro again, and Bets watched her in dismay. She didn’t like people who shouted and howled.

‘You’re all against me, you are!’ wailed Mrs. Moon. ‘Not a friend have I got in the world! You’re all against me!’

‘You have only yourself to blame, my good woman,’ said Inspector Jenks sharply. ‘You yourself are apparently filled with spite against a great many people - and you cannot be surprised if you have no friends. I’m afraid you must come with me for further questioning. Mrs. Hilton, I fear that Mrs. Moon will not be returning to you.’

‘I don’t want her,’ said Mrs. Hilton, with a shudder. ‘A cruel, underhand, spiteful woman like that in my house! No, never. Poor Gladys. I’ll fetch her back at once. I’m horrified and disgusted, Mrs. Moon. You have caused a great deal of pain and grief to many people, and I hope you will be well punished.’

‘You don’t mind us having investigated the case now, Mother, do you?’ said Pip, thinking this was a good opportunity to get his mother to agree.

‘Well - I didn’t want you mixed up in such an unpleasant business,’ said Mrs. Hilton. ‘And I must say that I thought Mr. Goon could manage it himself. But I do think you worked out things very cleverly - especially Fatty, of course.’

‘Oh, all the Find-Outers did their bit,’ said Fatty loyally. ‘I couldn’t have done without them. And,’ he said, with a glance at Mr. Goon, ‘we did have a lot of fun at times - didn’t we, Pip?’

‘We did!’ said all the others, and grinned at poor Mr. Goon, who did one of his snorts, and scowled heavily at them.

The Inspector got up. ‘Get your outdoor things, Mrs. Moon,’ he said. ‘You must come with me. Goon, I want you too. But perhaps, when I have finished my work here, at about four o’clock this afternoon, Mrs. Hilton, the children could come over to Nutting, where I’m going then, and have tea with me in the big hotel there? I feel I would like to have a little chat with the Five Find-Outers - and Dog - again!’

‘Oooh!’ said Bets, delighted.

‘Woof,’ said Buster, pleased.

‘Oh thanks!’ said the others.

Mrs. Moon went out, weeping. The Inspector shook hands with Mrs. Hilton and went out to his car. ‘See you this afternoon!’ he said, to the delighted children.

Mrs. Hilton went out to see that Mrs. Moon did what she was told. The children followed the Inspector to his big black car. Mr. Goon was left behind in the drawing-room, looking gloomily at the carpet. He was alone with his thoughts.

No - he wasn’t alone! Buster was there too, regarding his old enemy with a bright eye. No one was there to say, ‘Come here, Buster!’ What a chance!

With a joyful yelp he flung himself at Mr. Goon’s ankles, and pulled at his blue trousers. Mr. Goon rose up in alarm.

‘Clear-orf!’ he yelled. ‘Clear-orf, you! Leave my trousers alone! You want reporting, you do. Clear-orf!’

The children heard the shouting and laughed at the familiar words. ‘Poor old Clear-Orf,’ said Bets. ‘Always in trouble. Fatty, go and rescue him.’

Fatty went. Mr. Goon came out, frowning, trying to see if his trouser-ankles had been torn. Buster struggled in Fatty’s arms.

‘Get in, Goon, whilst you’re safe,’ said the Inspector, opening the door of the car. ‘Ah, here is Mrs. Moon. The other side, please, Mrs. Moon. Goodbye, children - and thanks for your help once more. I must say I’m pleased with the Five Find- Outers and Dog!’

‘Oh well - I suppose we ought to thank Mr. Goon for all those clues!’ said Fatty. He winked at the others, and they all opened their mouths together at once and chanted:

‘THANKS, MR. GOON!’

And what did Mr. Goon reply? Exactly what you would expect.

‘GAH!’