"My school -- the Priory School near Mackleton -- is the best school for young boys in England," began Dr Huxtable. "We have the sons of Lord Soames, Lord Lever, and of many other important people. Three weeks ago Mr James Wilder, the Duke of Holdernesse's secretary, came to see me. The Duke, he said, wanted to send his son, the ten-year-old Lord Saltire, to my school.

"On the 1st of May young Lord Saltire arrived. He's a nice boy, and he soon began to like school life and to make friends. His life at home, you see, was not very happy -- we all know about the Duke and his wife. The Duchess, of course, now lives in the south of France. She left the Duke about three months ago, I think. But the boy loved his mother, and was very unhappy when she left. Because of this, the Duke sent him to my school. And after two weeks with us, he was much happier.

"Then, on the night of the 13th of May, he disappeared. The way to his bedroom is through another, larger room. Two older boys sleep there. One of them never sleeps very well, and he heard and saw nothing that night. So young Arthur did not go out through that room. His window was open, and there is ivy all up the wall of the house. It is easy to get out of the window and down the ivy to the ground. So we think that he went out that way.

"He was in his usual school things, we think -- a short black coat and dark blue trousers. We looked all through his room very carefully, but we found nothing strange, nothing unusual.

"Heidegger came to the school a year ago. He's a good teacher, but the boys don't like him because he isn't very friendly.

"When I learnt the news at seven o'clock on Tuesday morning, I called everybody into the big schoolroom. Then we learnt more bad news -- Heidegger, the German teacher, was missing too. His room is not far from Arthur's room. Heidegger went down the ivy -- we know this because we found his footprints on the ground under the window. We know, too, that he was only in his coat, trousers, and shoes, because we found his shirt and his socks on the floor of his room. And he took his bicycle with him.

"So, Mr Holmes, we have two missing people. It's now Thursday, and there's still no news of them."

Holmes took out a little notebook, and began to write things down.

"No, no. We asked at Holdernesse Hall at once," said Dr Huxtable. "The Duke is very afraid for his son -- and I am the unhappiest man in England. Mr Holmes, you are a famous detective -- please help me!"

"The boy didn't go home, of course," he said.

"You make things very difficult for me," Holmes said. "How can I find marks in the ivy or on the ground after three days? Why didn't you come to me at once?"

"And what are the police doing?"

"Well, they heard about a boy and a young man at the station early on Tuesday. They looked for them, and last night they found them in Liverpool -- but it was a man and his son going to visit a friend. We lost three days because of that. And last night I couldn't sleep, so I took the first train down to London this morning."

"Because of the Duke," Dr Huxtable said. "He doesn't like people talking about his unhappy family life."

"No."

"So he didn't know the German teacher well, then."

"Well, Dr Huxtable, some more questions," said Holmes. "Did the boy take German lessons?"

"No, I never saw any."

"Yes, one letter. From his father."

"Did the boy get any letters from France?"

"I know the Duke's handwriting. And he says that he wrote a letter to his son."

"Then how do you know that the letter was from the father?"

"So. Did the German teacher ride away on his bicycle in the night, with the boy on his back? I don't think so. But what happened to the bicycle? Now, what about visitors? Did the boy have any visitors the day before?"

"Do you open the boys' letters, Dr Huxtable?"

"I don't know," said Dr Huxtable. "He only had letters from his father, I think."

"Mmm," said Holmes. "Does the boy have a bicycle?"

"Did he get any letters?"

"No."

"No."

"No."

"Do you understand me, Dr Huxtable?" Holmes said. "Did someone take the boy away, or did the boy go freely? -- because he had a letter from France perhaps."

"No."

"He probably never spoke to him," said Dr Huxtable.

"Was any other bicycle missing?"

"I see," said Holmes. "That last letter of the Duke's -- where is it now?"

"Mr James Wilder, the Duke's secretary, told me."

"No."

"Oh no! The Duke never talks about things like that."

"Did he say that?"

"Did the Duke tell you, then?"

"The Duke is not… er… not a very friendly man, Mr Holmes. He's not a bad father, but he is a Government Minister and has a lot of things to do."

"So how do you know?"

"Right," said Holmes. He looked at me. "Watson, let's get ready and go off to the north with Dr Huxtable. Perhaps we can find some answers to this mystery."

"So the boy felt more friendly to his mother?"

"Yes."

"The boy took it with him," Dr Huxtable said. "It's not in his room. Mr Holmes -- our train leaves in half an hour."

"Were father and son very friendly?"