‘Oh,’ said the children, really quite relieved at this explanation.

‘So that’s it!’ said Pip, without thinking.

‘That’s what?’ asked Mrs. Moon sharply.

‘Nothing,’ said Pip hastily, feeling a nudge from Fatty. ‘Nothing at all!’

Mrs. Moon looked at the children curiously. Fatty got up. He didn’t want to make Mrs. Moon suspicious about anything.

‘Time I went,’ he said. ‘Your lunch will get cold, Pip and Bets, if you don’t go and have it. See you later.’

‘Here’s your notebook, Fatty!’ Bets called after him, as he went downstairs. ‘Your precious notebook with all its Clues and Suspects! Fatty, are you going to write up the case again? You’ve got some more to put down now, haven’t you?’

‘Chuck the book down to me,’ said Fatty. ‘Yes, I’ll write up the case as far as it’s gone. I bet old Goon would like to see my notes!’

He went out of the garden-door with Larry and Daisy. Fatty did not put on his wig or apron again. He stuffed them into his bicycle basket.

‘Good thing I’d taken them off before Mrs. Moon came in,’ he said. ‘She’d have wondered why you were hobnobbing with the butcher-boy!’

‘Fatty, who do you think is the letter-writer?’ said Daisy, who was burning with curiosity. ‘I think it’s Mrs. Moon. I do really.’

‘I do too,’ said Larry. ‘But I don’t see how we are to get any proof.’

‘Yes, it certainly might be Mrs. Moon,’ said Fatty thoughtfully. ‘You remember that Pip told us she wanted her niece to come here? She might have got Gladys out of the way for that. And yet - there are all the other letters too. Whoever wrote them must be a bit mad, I think.’

‘What do we do next?’ asked Larry.

‘I think we’ll try and find out a bit more about Mrs. Moon,’ said Fatty. ‘We’ll meet at Pip’s at half-past two.’

When they arrived back at Pip’s, they found him and Bets in a great state of excitement.

‘What do you think! Old Clear-Orf is here and he’s been going for Mrs. Moon like anything!’ cried Pip. ‘We heard a lot of it, because the kitchen window’s open and it’s just under our playroom!’

‘What’s he been going at her for? ’ asked Fatty.

‘Well, apparently she used to live near the Home where Gladys was,’ said Pip. ‘And once she was working there as cook, and she got the sack because the girls complained of her bad temper. Maybe Gladys was one of those that complained! Old Clear-Orf has been making inquiries himself, I suppose, and when he found out that Mrs. Moon actually knew the Home Gladys had been in, I suppose he came over all suspicious. He shouted at her like anything - and she shouted back!’

A noise of voices arose again. The children leaned out of the window.

‘And what right have you got to come here and talk to an innocent woman like you have!’ shouted Mrs. Moon. ‘I’ll have the law on you!’

‘I am the Law,’ came Mr. Goon’s ponderous voice. ‘I’m not accusing you of anything, Mrs. Moon, please understand that. I’m just asking you a few questions in the ordinary way of business, that’s all. Routine questions is what we call them. Checking up on people, and finding out about them. Clearing them if they’re innocent - as I’ve no doubt you are. You didn’t ought to go on like this just because the Law asks you a few civil questions!’

‘There’s others you could well ask questions of,’ said Mrs. Moon darkly. ‘Yes, others I could tell you of.’

‘I’ve got a list of people I’m asking questions of,’ said Mr. Goon. ‘And all I hope is they’ll be more civil than you’ve been. You don’t make a good impression, Mrs. Moon, you don’t, and that’s flat.’

Whereupon Mr. Goon took his departure, and cycled slowly and heavily up the drive, the back of his neck looking bright red with rage.

‘Old Goon’s a bit brighter than we think,’ said Fatty. ‘He seems to have got his list of Suspects just as we have - and Mrs. Moon is down on his too!’

‘I thought when he saw you posting that letter yesterday at Sheepsale he’d suspect you!’ said Larry.

‘Oh, I think he’s sure I’m “messing about” somehow, as he puts it,’ said Fatty. ‘He’s probably expecting someone to get a stupid letter from me, as well as from the real letter-writer. Well - I’ve a jolly good mind to let him have one!’

‘Oh no, Fatty!’ said Daisy.

Fatty grinned. ‘No, I didn’t mean it. Well, let’s go out into the garden, shall we? We’ll go up to that old summer-house. I’ll write up my notes there, whilst you all read or do something. It’s too hot to stay indoors.’

They all went up to the summer-house. It backed on to the next-door garden, and was a nice, secluded little place, well away from the house. The children pulled some early radishes from the garden and washed them, meaning to nibble them all the afternoon.

They all talked hard about their mystery. They discussed everything and everybody. They read out loud what Fatty had written. It sounded very good indeed. He had even written up the interview between Mr. Goon and Mrs. Moon that afternoon. It began:

‘Said Mr. Goon

To Mrs. Moon’

and went on in such a funny strain that the children roared.

Then, quite suddenly, they heard voices very near them. They stopped their talk, startled. Who could be so near?

They peeped out of the summer-house. They saw Mrs. Moon, with some lettuces in her hand, talking to a stranger over the wall, almost within touch of their summer-house.

‘Well, that’s what I always say, Miss Tittle,’ they heard Mrs. Moon say. ‘If a thing’s too tight, it’s not worth wearing!’

‘You’re quite right,’ said the little, neat woman looking over the wall. ‘But people will have their things made so tight. Well, do come in and see me about that dress of yours, Mrs. Moon, sometime. I’d enjoy a good talk with you.’

‘I bet she would,’ whispered Daisy. ‘The two of them together would just about pull every one in Peterswood to pieces!’

‘Miss Tittle didn’t look a very nice person,’ said Bets, watching Mrs. Moon go down the path with her lettuces. She had obviously just been up the kitchen garden nearby to pull them.

‘I suppose you realize that we’ve been talking very loudly, and that both Miss Tittle and Mrs. Moon could have heard every word, if they’d been listening?’ said Fatty, witn a groan. ‘I never thought of anyone coming up here. Miss Tittle must have been just the other side of the wall, and Mrs. Moon must have come up to get the lettuces. They grow quite near the summer-house. Now both will be on their guard, if they’ve heard what we’ve been saying!’

‘They won’t have heard!’ said Pip.

‘They may quite well have done,’ said Fatty. ‘What idiots we are. Really! Giving all our clues and facts away at the tops of our voices. And Bets reading out loud from my notes!’

‘Why didn’t Buster bark?’ said Bets.

‘Well, he knows Mrs. Moon all right and wouldn’t bark if she came by,’ said Fatty. ‘And I don’t expect he bothers about anyone in the next garden. Do you, Buster, old fellow?’

‘Woof,’ said Buster lazily. He was lying in a patch of sun and it was pleasantly warm on him. He cocked his ears up, hoping to hear the magic word ‘Walk.’

He soon heard it. ‘I vote we go for a walk,’ said Larry. ‘It’s getting stuffy here. Let’s go down to the river and watch the swans. We’ll take some bread.’

Pip asked Mrs. Moon for some bread. She seemed sulky and upset. ‘No wonder,’ thought Pip, ‘after having Mr. Goon bellowing at her!’

They had a lovely time by the river. They sauntered back to tea, but parted at Pip’s, because each had to get back home for tea that afternoon.

‘See you tomorrow,’ said Fatty. ‘We seem to be rather stuck again, don’t we? This mystery wants oiling a bit! Well - maybe something will happen tomorrow!’

Fatty was quite right. Plenty happened - and it was very exciting too!