The thing that puzzled everyone, the police included, was — how did the thief or thieves get in? Both policemen went round the house, slowly and deliberately trying every door and window still locked or fastened. They stood and looked at the pantry window for some time.

“Got in there, I suppose,” said one of them.

“Must have been as small as a monkey then,” said the other. He turned to Anne, who was the smallest of the four children. “Could you squeeze through there, Missy, do you think?”

“No,” said Anne. “But I’ll try if you like.” So she tried — but she stuck fast before she got even half-way through, and Julian had to pull hard to get her down again.

“Have you any idea what has been stolen, sir?” the sergeant asked Julian, who seemed extraordinarily grown-up that morning.

“No, sergeant — none of us has,” said Julian. “Not even George here, who knows her father’s work better than any of us. The only thing we know is that my uncle went to America to lecture a short time ago — and he brought back two notebooks, full of valuable diagrams and notes. He did say that other countries might be very glad to get hold of those. I expect they were in that safe.”

“Well — they’ll certainly be gone then,” said the sergeant, shutting his own fat notebook with a snap. “Pity when people leave such things in an ordinary safe — and then go off without leaving an address. Can’t we possibly get in touch with him? This may be terribly important.”

“I know,” said Julian, looking worried. “We shall have an address in a day or two — but I honestly don’t see how we can get in touch before then.”

“Right,” said the sergeant. “Well — we’ll go now — but we’ll bring back a photographer with us after lunch to photograph the room — then your cook can tidy it up. I know she’s longing to.”

“Coming back again!” said Anne, when the two men had solemnly walked down the path, mounted very solid-looking bicycles, and gone sailing down the lane. “Good gracious! Have we got to answer questions all over again?”

“Well, we’ll go down to the beach and take a boat and go rowing,” said Julian, with a laugh. “We’ll be out of reach then. I don’t see that we can give them any more help. I must say it’s all very peculiar — I wish to goodness I knew how the thief got in.”

George had been very quiet and subdued all the morning. She had worried about Timmy, fearing that he had been poisoned, and not merely drugged, as Julian had said. But Timmy was now quite recovered, except that he seemed a bit sleepy still, and not inclined to gambol round in his usual ridiculous way. He looked extremely sheepish, too.

“I can’t think why Timmy looks like that,” said George, puzzled. “He usually only puts that look on when he’s done something he’s ashamed of — or got into mischief. He couldn’t possibly know, could he, that whatever he picked up and ate last night was something he shouldn’t eat?”