‘I had a marvellous report again,’ said Fatty. ‘Did you, Pip?’

‘You know I didn’t,’ said Pip. ‘You heard my mother say so. Shut up, Fatty.’

‘Let’s talk about our new mystery,’ said Daisy, seeing that a quarrel was about to flare up. ‘Write down some notes, Fatty. Let’s get going.’

‘I was just about to,’ said Fatty, rather pompously. He printed in beautiful small letters a heading to the page in the lovely leather notebook he held. The others looked to see what he had printed:

MYSTERY NO. 4. BEGUN APRIL 5TH.

‘Ooh - that looks fine,’ said Bets.

‘CLUES’ was the next thing printed by Fatty, over the page.

‘But we haven’t got any,’ said Pip.

‘We soon shall have,’ said Fatty. He turned over the page. ‘SUSPECTS’ was what he printed there.

‘We don’t know any of those yet either,’ said Daisy. ‘And I’m sure I don’t know how we’re going to find any.’

‘Leave it to me,’ said Fatty. ‘We’ll soon have something to work on.’

‘Yes, but what?’ said Pip. ‘I mean, it’s no use looking for footprints or cigarette-ends or dropped hankies or anything like that. There’s just nothing at all we can find for clues.’

‘There’s one very important thing,’ said Fatty.

‘What’s that?’ said everyone.

‘That anonymous letter,’ said Fatty. ‘It’s most important we should get a glimpse of it. Most important!’

‘Who’s got it?’ asked Larry.

‘My mother might have it,’ said Pip.

‘More likely Gladys has got it,’ said Fatty.

‘That’s the first thing we must do. Go and see Gladys, and ask her if she knows or guesses who could have written her that letter. We must also find out what’s in it.’

‘Let’s go now,’ said Pip, who always liked to rush off as soon as anything had been decided.

‘Right. You take us,’ said Fatty. Pip looked rather blank.

‘But I don’t know where Gladys lives,’ he said.

‘Ha, I thought you didn’t,’ said Fatty. ‘Well, Pip, you must find out. That’s the first thing we’ve got to do - find out where Gladys lives.’

‘I could ask Mother,’ said Pip doubtfully.

‘Now don’t be such a prize idiot,’ said Fatty at once. ‘Use your brains! You know jolly well your parents don’t want us mixed up in this mystery, and we’ve got to keep it dark that we’re finding out things. Don’t on any account ask your mother anything - or Mrs. Moon either.’

‘Well, but how am I to find out then?’ said Pip, looking bewildered.

‘I know a way, I know a way!’ sang out Bets suddenly. ‘Gladys lent me a book once and I didn’t have time to give it her back before she left. l could go to Mrs. Moon and tell her, and ask her for Gladys’s address so that I could send the book on to her.’

‘Clever girl!’ said Fatty. ‘You’re coming on well, you are, Bets! Perhaps you’d better handle this, and not Pip.’

‘I’ve got an idea too now,’ said Pip, rather sulkily.

‘What?’ said Bets.

‘Well - if I got a bit of paper and stuck it in an envelope, and wrote Gladys’s name and our address on it and posted it - Mother would re-address it and I could hang about and see what it was, when she puts the letter on the hall-stand to be posted,’ said Pip.

‘Yes, that’s a very fine idea too,’ said Fatty. ‘Couldn’t have thought of a much better one myself. Go to the top of the class, Pip.’

Pip grinned. ‘Well - both Bets and I will carry out our ideas,’ he said, ‘and surely one of us will get Gladys’s address!’

‘Here’s a bit of paper and an envelope,’ said Fatty. ‘But disguise your writing, Pip.’

‘Why?’ said Pip, surprised.

‘Well - seeing that your mother gets a letter from you every single week when you’re away at boarding-school, it’s likely she might recognize your writing and wonder why on earth you were writing to Gladys when she was gone!’ said Fatty, in a very patient, but rather tired voice.

‘Fatty thinks of everything!’ said Daisy admiringly. Pip saw the point at once, but doubted very much if he could disguise his writing properly.

‘Here - give it to me. I’ll do it,’ said Fatty, who was apparently able to disguise his writing as easily as he could disguise his appearance and his voice. He took the envelope, and, to the children’s enormous admiration, wrote Gladys’s name and Pip’s address in a small, extremely grown-up handwriting, quite unlike his own.

‘There you are,’ he said. ‘Elementary, my dear Pip!’

‘Marvellous, Mr. Sherlock Holmes!’ said Pip. ‘Honestly, Fatty, you’re a wonder. How many different writings can you do?’

‘Any amount,’ said Fatty. ‘Want to see the writing of a poor old charwoman? Here it is!’

He wrote a few words in a scrawling, untidy writing. ‘Oh, it’s just like Mrs. Cockles’s writing!’ cried Bets in delight. ‘Sometimes she puts out a notice for the milkman - “TWO PINTS” or something like that - and her writing is just like that!’

‘Now write like old Clear-Orf,’ said Larry. ‘Go on! What does he write like?’

‘Well, I’ve seen his writing, so I know what it’s like,’ said Fatty, ‘but if I hadn’t seen it I’d know too - he’d be bound to write like this....’

He wrote a sentence or two in a large, flourishing hand with loops and tails to the letters - an untidy, would-be impressive hand - yes, just like Mr. Goon’s writing.

‘Fatty, you’re always doing something surprising,’ said Bets, with a sigh. ‘There’s nothing you can’t do. I wish I was like you.’

‘You be like yourself. You couldn’t be nicer,’ said Fatty, giving the little girl a squeeze. Bets was pleased. She liked and admired Fatty very much indeed.

‘You know, once last term I thought I’d try out a new handwriting on my form-master,’ said Fatty. ‘So I made up a marvellous handwriting, very small and neat and pointed, with most of the letters leaning backwards - and old Tubbs wouldn’t pass it - said I’d got some one to do that prep for me, and made me do it all again.’

‘Poor Fatty,’ said Bets.

‘Well, the next time I gave my prep in, it was written in old Tubbs’ own handwriting,’ said Fatty, with a grin. ‘Golly, it gave him a start to see a prep all done in his own writing!’

‘What did he say? ’ asked Pip.

‘He said, “And who’s done this prep for you this time, Trotteville?” And I said, “My goodness, sir, it looks as if you have!” ’ said Fatty. The others roared with laughter. Whether Fatty’s school tales were true or not, they were always funny.

Pip slipped the blank piece of paper into the envelope that Fatty had addressed and stuck it down. He took the stamp that Fatty offered him and put it on.

‘There!’ he said. ‘I’ll post it on my way home tonight. It’ll catch the half-past six post and it will be there tomorrow morning. Then if I don’t manage to spot the re-addressed letter my name isn’t Pip.’

‘Well, it isn’t,’ said Bets. ‘It’s Philip.’

‘Very funny!’ said Pip. ‘I don’t think!’

‘Now don’t squabble, you two,’ said Fatty. ‘Well, we’ve done all we can for the moment. Let’s have a game. I’ll teach you Woo-hoo-colly-wobbles.’

‘Gracious! Whatever’s that?’ said Bets.

It was a game involving much woo-hoo-ing and groaning and rolling over and over. Soon all the children were reduced to tears of mirth. Mrs. Trotteville sent up to say that if anybody was ill they were to go down and tell her, but if they were just playing, would they please go out into the garden, down to the very bottom.

‘Oooh. I didn’t know your mother was back,’ said Pip, who had really let himself go. ‘We’d better stop. What an awful game this is, Fatty.’

‘I say - it’s almost half-past six!’ said Larry. ‘If you’re going to post that letter, you’d better go, young Pip. Brush yourself down, for goodness sake. You look awful.’

‘Gah!’ said Pip, remembering Mr. Goon’s last exclamation. He brushed himself down, and re-tied his tie. ‘Come on, Bets,’ he said. ‘Well, so long, you others - we’ll tell you Gladys’s address tomorrow, and then we’ll go and see her and examine our first clue - the “nonnimus” letter!’