Mystery of the Spiteful Letters by Enid Blyton

said she had to go to her sister, who was upset because she’d had a nasty letter. Don’t let on that you know any more than that.’
    ‘Right,’ said Pip. ‘Well, you hop off now, Fatty, before old Goon gets going on the job. He’ll be round at Mrs. Cockles’s sister in no time, as soon as he hears about the letter.’
    Fatty shot off. He knew where Willow Lane was. He found number 9 and went to the little front door. It was a dirty, untidy little place. He rapped on the wooden door.
    ‘Come in!’ called Mrs. Cockles’s voice. ‘Oh, it’s you, Master Frederick. Well, my sister says she won’t show you the letter. She says what’s in it isn’t for anyone to read but me and the police. And I won’t say but what she’s right, now I’ve read the letter properly.’
    Fatty was most bitterly disappointed. ‘Oh, I say!’ he said. ‘You might just let me have a squint. I’ve seen all the others. Go on, be a sport and let me see it.’
    Mrs. Cockles’s sister was a fat, untidy woman, who breathed very loudly through her mouth and talked through her nose.
    ‘’Taint fit for a child to read,’ she said. ‘It’s a right down spiteful letter, and not a word of truth in it, neither!’
    ‘I’m not a child!’ said Fatty, making himself as tall as he could. ‘You can trust me to read the letter and not say a word to anyone. I’m - er - I’m investigating the case, you see.’
    Mrs. Cockles was very much impressed. But she still agreed with her sister that the letter was not one for him to read. Fatty, of course, was not in the least curious about its contents - but he did badly want to see the printing and, of course, the envelope.
    ‘Well - could I just see the envelope!’ he asked. ‘That would do quite well.’
    Neither Mrs. Cockles nor Mrs. Lamb, her sister, could see any reason why he should not see the envelope. They handed it to him. Fatty looked at it eagerly, to make out the post-mark.
    But there was none! There was no stamp, no post-mark! Fatty stared in surprise.
    ‘But - it didn’t come by post!’ he said.
    ‘I never said it did,’ said Mrs. Lamb. ‘It come this morning, very early - about half-past six, I reckon. I heard something being pushed under the door, but I was too sleepy to get up. So I didn’t get it till about half-past eight - and then I was that upset, I sent for Mrs. Cockles here. And you come at once, didn’t you, Kate?’
    ‘Course I did,’ said Mrs. Cockles. ‘Only stopped to have a word with Mr. Goon about it. He’ll be along soon to have a look at the letter too.’
    Fatty felt slightly alarmed. He didn’t want to bump into Clear-Orf at the moment. He stared hard at the envelope once more. The name and address were printed in capital letters again, and the square envelope was the same as the others that had been used. Fatty took his notebook out of his pocket and looked at the page headed CLUES.
    He compared the tracing of the word PETERSWOOD with the same word on the envelope. Yes, there was no doubt at all, but that the same hand wrote both words. They were exactly alike.
    Fatty handed the envelope back to Mrs. Lamb. He had got from it all he wanted. He didn’t want to see the letter inside. He could imagine it - a few sentences of spite and hurtfulness, with perhaps a little truth in them. He had enough to puzzle himself with - here was the usual letter, received on a Tuesday morning - but this time not through the post, and not from Sheepsale. Funny!
    ‘Well, I’ll be going,’ said Fatty. ‘Thanks for showing me the envelope, Mrs. Lamb. I’m so sorry you had one of these beastly letters. I shan’t rest till I find out who is the writer of them.’
    ‘Mr. Goon, he’s on to them too,’ said Mrs. Cockles. ‘Says he’s got a very good idea who it is, too.’
    Fatty doubted that. He was sure that Mr. Goon was as puzzled as he was. He said good-bye and went out of the dirty little room.
    But coming in at the front gate was the burly figure of Mr. Goon! Fatty was annoyed. He tried to get out of the gate before Mr. Goon came