I came down to breakfast the next morning and found Sir Walter reading a coded message. He seemed less relaxed than yesterday.

While I ate, he continued to talk. I was surprised that he was telling me all these important secrets.

"Can't the Navy's war plans be changed?" I asked.

"They could," he said. "But we want to avoid that. It would be very difficult, and some changes would be impossible. But the big problem is that they're not going to steal the plans in the street. They'll try to get the details without anybody knowing, and Royer will return to Paris thinking that every-thing is still secret."

"I was very busy for an hour after you went to bed," he said. "I've arranged for the Frenchman, Royer, to come a day early. He will be in London at five o'clock. I don't think the change of day will help very much. If our enemies already knew he was coming, they will probably find out that the plans have changed. I would love to know how the news of his visit escaped."

"Then we must stay at Royer's side until he is home again," I said.

After breakfast he asked me to be his driver for the day.

"Royer will meet us after dinner at my house in London: there'll be Whittaker from the Navy, myself, Sir Arthur Drew, and General Winstanley. The First Sea Lord, the head of the Navy, has been ill, and may not be able to come. Whittaker will give Royer the important papers, and then Royer will be driven to Portsmouth where a Navy ship will take him to France. He will be watched until he is back there. Whittaker will be watched while he has the papers before he meets Royer. It's the best we can do, and I don't see what can go wrong. But I'm very nervous because of the murder of Karolides. "

"You know what these people are like, and I don't want to take risks."

"I've brought you the Langham Place murderer," said Sir Walter.

In London we went first to Scotland Yard where we met an important-looking policeman.

"Mr Hannay will interest you again, MacGillivray, but his story must wait twenty-four hours. But I would like you to tell Mr Hannay that you don't want to arrest him any more."

The policeman smiled. "I wish you had. I imagine you are Mr Hannay. We were very interested in you for a few days."

"Of course we don't." The policeman turned to me. "Your flat and your servant are waiting for you, although you may not want to return there."

As Sir Walter and I left, he said I was free for the rest of the day. "Come and see me tomorrow, Hannay. I don't need to tell you to keep everything secret. You had better stay out of sight. If your Black Stone friends see you, there might be trouble."

I didn't know what to do. It was strange to be a free man. I went to a very good restaurant for lunch, but I was still feeling nervous. When anybody looked at me, I wondered if they were thinking about the murder. I walked around London, thinking. I knew that by now Royer would be in England, and I felt sure that something terrible was going to happen and that only I could stop it. But it was not my business now.

I had supper in another restaurant, and thought that after that I would go to Sir Walter's house. He might not want me there, but I would feel happier if I went.

I didn't want to go back to my flat. I had to go back some time, but I decided to stay at a hotel tonight.

I didn't want trouble, but I was feeling angry. A policeman came up, and instead of explaining the mistake to him quietly and sensibly, I just hit out wildly at Marmaduke's stupid face. I felt much happier when he was lying on his back in the road. Then a general fight started, until the policeman got hold of me. I heard him ask what the matter was, and Marmaduke, talking through his broken teeth, told him that I was Hannay the murderer.

As I walked through London towards his house, I met a group of young men. One of them was Marmaduke Jopley.

"It's the murderer!" he cried. "Stop him! That's Hannay, the Langham Place murderer!" He took hold of my arm, and the others crowded round me.

I was so angry that I pushed the policeman one way and one of Marmaduke's friends the other, and ran as fast as I could. There was shouting behind me, but I had escaped. I ran all the way to Sir Walter's house, walked up to the door and rang. I hoped the door would open quickly.

It did.

"I must see Sir Walter," I said to the servant. "It's desper ately important."

"Listen," I whispered to the servant. "I'm in a bit of trouble, but I'm working for Sir Walter. If anyone comes to the door and asks for me, tell them I'm not here."

The servant let me in, and then shut the door behind me. "Sir Walter is in a meeting, sir. Perhaps you will wait."

There was a sudden ringing at the door, and he went to open it. He told them whose house it was, and that nobody could come in, and then shut the door.

A few minutes later there was another ring at the door, and the servant did not hesitate to let this visitor in. Everybody knew his face from the newspapers -- a square, grey beard and bright blue eyes Lord Alloa, the First Sea Lord, and head of the British Navy.

He was shown into a room at the end of the hall. I sat there for twenty minutes. Surely the meeting would end soon; Royer must leave for Portsmouth by eleven o'clock.

Then the door opened again and the First Sea Lord came out. He walked past me, and in passing he looked at me and for a second I looked into his eyes. It was only for a second, but my heart jumped. The First Sea Lord had never seen me before, but in his eyes I saw that he recognized me. Then he passed me and was out of the door into the street.

There was a telephone and one or two chairs in the hall, and I sat down there.

Sir Walter looked surprised and annoyed. "I'm afraid that this is not a good time, Mr Hannay."

"It Was not," I cried. "It looked like him but it was not him. It was a man who recognized me, who has seen me in the last month. I've just telephoned Lord Alloa's house and he's been ill in bed all day."

I picked up the telephone book and looked up the number of Lord Alloa's house. I spoke to one of his servants.

"Who…" someone asked.

"Lord Alloa," said Sir Walter, looking angrier.

"Yes, but he's ill and has been in bed all day. Do you want to leave a message, sir?"

I put down the telephone and sat down, shaking. My part in this business was not finished. I walked straight into the room where the others were meeting.

"Is Lord Alloa at home?" I asked.

"The Black Stone," I cried, sitting down, and looking at five frightened men.

"I think it is," I answered. "Tell me, please, who left this room a minute ago."