The information he brought back was neither good nor bad.

After breakfast we walked along the beach under the Ruff. I kept hidden, while MacGillivray counted the six lots of steps in the cliff.

I waited for an hour while he counted, and when I saw him coming towards me with a piece of paper, I was very nervous.

It was a fine, blue June morning, and I was outside a hotel in Bradgate looking out to sea. There was a ship out there, and I could see that it was a warship of some kind. Mac Gillivray had been in the navy and knew the ship. I sent a message to Sir Walter to ask if it could help us if necessary.

The house was called Trafalgar House, and belonged to an old man called Appleton. He was there at the moment. The neighbours didn't know him well. MacGillivray had then gone to the back door of the house, pretending to be a man selling sewing machines. There were three servants, and he spoke to the cook. He was sure she knew nothing. Next door a new house was being built, which might be a good place to watch from; and on the other side the house was empty. Its garden was rather wild, and would also be a good place to hide in.

He read out the numbers. "Thirty-four, thirty-five, thirtynine, forty-two, forty-seven, and twenty-one." I almost got up and shouted.

We walked back to Bradgate quickly. MacGillivray had six policemen sent down from London. He then went off to look at the house at the top of the thirty-nine steps.

After lunch I sat in front of the hotel and looked out to sea; and then I felt happier, because I saw something new. A yacht came up the coast and stopped a few hundred metres off the Ruff MacGillivray and I went down to the harbour, got a boat, and spent the afternoon fishing.

We caught quite a lot of fish, and then, at about four o'clock, went to look at the yacht. It looked like a fast boat and its name was the Ariadne. I spoke to a sailor who was cleaning the side of the boat, and he was certainly English. So was the next sailor we spoke to, and we had quite a long conversation about the weather.

I wasn't feeling very confident. That old man might be the old man I had met in the farmhouse on the moors. But there are hundreds of old men in houses by the sea, and he was probably just a nice old man on his holidays.

I took a telescope and found a good hiding place from which to watch the house. I watched for a time, and saw an old man leave the house and walk into the back garden at the top of the cliff. He sat down to read a newspaper, but he looked out to sea several times. I thought he was probably looking at the warship I watched him for half an hour, until he went back into the house for lunch. Then I went back to the hotel formine.

I felt a little more confident after seeing him, but as we went back to Bradgate, I was still not sure. My enemies had killed Scudder because they thought he was a danger to them. They had tried to kill me -- for the same reason. So why hadn't they changed their escape plans? They didn't know about Scudder's black notebook, but why stay with the same plan when there was a chance that I knew about it? It seemed a stupid risk to take.

Then, suddenly, the men stopped talking and started work again, and a man in uniform walked up. He was a pleasant, friendly man, and asked us about the fishing in very goodEnglish. But I was sure that he was not English himself.

I decided to spend an hour or two watching Trafalgar House and found a good place where I could look down on the garden. I could see two men playing tennis. One was the old man I had already seen; the other was a younger, fatter man. They played well, and were clearly enjoying themselves like two businessmen on holiday. I have never seen anything more harmless. They stopped for a drink, and I asked myself if I wasn't the most stupid man alive. These were two normal, boring Englishmen, not the clever murderers that I had met in Scotland.

Then a third man arrived on a bicycle. He walked into the garden and started talking to the tennis players. They were all laughing in a very English way. Soon they went back into the house, laughing and talking, and I stayed there feeling stupid.

These men might be acting, but why? They didn't know I was watching and listening to them. They were just three perfectly normal, harmless Englishmen.

But there were three of them: and one was old, and one was fat, and one was thin and dark. And a yacht was waiting a kilometre away with at least one German on it. I thought about Karolides lying dead, and all Europe trembling on the edge of war, and about the men waiting in London, hoping that I would do something to stop these spies.

I decided there was only one thing to do. I had to continue and just hope for the best. I didn't want to do it. I would rather walk into a room full of wild animals than walk into that happy English house and tell those three men they were under arrest. How they would laugh at me!

Then I remembered something that an old friend in Africa once told me. He had often been in trouble with the police. He once talked about disguises with me, and he said that the way somebody looked was not the real secret. He said that what mattered was the "feel" of somebody. If you moved to completely different surroundings, and if you looked comfortable and at home there, you would be very difficult to recognize. My friend had once borrowed a black coat and tie and gone to church and stood next to the policemen who was looking for him. The policemen had only seen him shooting out the lights in a pub, and he did not recognize him in a church.

My friend had also told me this: "If you want to disguise yourself, you must believe that you're the person you're pretending to be." That would explain the game of tennis. These men weren't acting; they just changed from one life to another, and the new life was as natural as the old. It is the secret of all great criminals.

It was now about eight o'clock. I went back to seeMacGillivray and we arranged where the other policeman would hide. After that I went for a walk along the coast, looking at the peaceful people on holiday. Out at sea I could see lights on the Ariadne, and on the warship, and, further away, the lights of other ships. Everything seemed so normal and peaceful that I couldn't believe the three men were my criminals. But I turned and walked towards Trafalgar House at about half past nine.

Perhaps these people were playing the same game. A stupid man tries to look different; a clever man looks the same and is different.

MacGillivray's men were, I supposed, in their hiding places. The house was quiet, but I could just hear the sound of voices; the men were just finishing their dinner Feeling very stupid, I walked up to the door and rang the bell.

I pulled up a chair and sat down.

When I walked in, the old man stood up and turned round to meet me. The other two turned to look at me. The old man was perfectly polite.

"Mr Hannay?" he said. "Did you wish to see me?"

When a servant opened the door, I asked for Mr Appleton and was shown in. I had planned to walk straight in and surprize the men into recognizing me. But I started looking at all the pictures on the wall There were photographs of groups of English schoolboys and lots of other things that you only find in an English home. The servant walked in front of me into the dining-room and told the men who I was, and I missed the chance of surprise.

"I think we've met before," I said, "and I guess you know why I'm here."

The light in the room was not bright, but I think they all looked very surprised.

"Perhaps, perhaps," said the old man. "I'm afraid I don't remember faces very well. You'll have to tell me why you're here, because I really don't know."

"Well," I said, although I didn't really believe what I was saying, "I have come to arrest all three of you."

"For the murder of Franklin Scudder in London on the 23rd of May."

"I've never heard the name before," said the old man.

One of the others spoke. "That was the Langham Place murder. I read about that in the newspapers. But you must be mad! Where do you come from?"

"Arrest!" said the old man in surprise. "Arrest! What for?"

"Scotland Yard," I said.

Then there was silence for a moment until the fat one started to talk, hesitating a lot between words.

"Don't worry, uncle. It's all a stupid mistake. Even the police make mistakes. I wasn't even in England on the 23rd, and Bob was in hospital. You were in London, but you can explain what you were doing."

"You're right, Percy, it's easy. The 23rd! That was the day after Agatha's wedding. Yes, I had lunch with Charlie Symons and in the evening I went to the Cardwells'. Why, they gave me that!" He pointed to a cigar box on the table.

"I think you will see that you have made a mistake," the thin dark man said to me politely. "We are quite happy to help Scotland Yard, and we don't want the police to make stupid mistakes. That's so, isn't it, uncle?"

"Yes, it's a good story. Really, Mr Hannay, I should be angry, but it's too funny. You really frightened me! You looked too serious. I thought I'd killed somebody in my sleep!"

"This will make our friends laugh," said the fat man. "They think we're boring and that nothing ever happens to us. Hebegan to laugh very pleasantly."

"Certainly, Bob." The old man looked happier now.

"Certainly we'll help if we can. But this is madness."

There was nothing to do except call in the men outside and arrest them, or say I had made a mistake and leave. And I couldn't decide.

I saw nothing to help me. One was old and bald, one was fat, one was dark and thin. They could be the three men I had seen in Scotland, but I could see nothing to prove it.

"Well," said the old man politely, "are you sure now that we are not murderers, or are you going to take us to the police station?"

They weren't acting. There was nothing false about them. At first I wanted to apologize and leave. Then I stood up and went to the door and turned on the main light. I looked at the three faces.

But the old man was the worst. How had I ever thought he looked kind and friendly? His eyes were cold and evil and frightening. I went on playing, but I hated him more and more with every card.

I agreed, but everything suddenly seemed unreal. We went into another room, where there was a table and cards. The window was open and the moon was shining on the cliffs and the sea. We played and they talked. I'm usually quite good at cards, but that night I played extremely badly.

Then something woke me up.

The three faces seemed to change in front of my eyes. The thin dark man was the murderer. His knife had killed Scudder. The fat man had been the First Sea Lord last night.

The old man put his cards down for a moment and sat back in his chair with his hand on his knee. It was a movement I had seen before, in that farm on the moors, with two servants with guns behind me. Suddenly my head cleared and I looked at the three men differently.

"While we're waiting, let's have a game of cards," said the fat one. "It will give Mr Hannay time to think, and we need a fourth player. Will you play?"

It was ten o'clock.

"I'm afraid he must wait,"I said.

"Look at the time, Bob," said the old man. "Don't forget you've got a train to catch. He must be in London tonight," he said, turning to me. His voice now sounded completely false.

"Oh, no!" said the thin man. "I thought you'd finished with that. I must go. You can have my address."

"No," I said,"you must stay."

Suddenly, the old man escaped from me and ran to the wall of the room. From underneath the ground I heard an explosion. The cliff and the steps had been blown up.

I think then they realized they were in real trouble. I looked at the old man and I saw his eyes hood like a hawk.

Immediately the lights went out. Someone held me to my chair.

I blew my whistle.

"Quickly, Franz," somebody shouted in German, "the boat, the boat!" I saw two policemen on the grass behind the house.

The thin dark man jumped through the window and was across the grass before anybody could stop him. I was fighting the old man, and more police came into the room. I saw them holding the fat man. But the thin man was at the top of the steps. I waited, holding the old man, for the time it would take the thin man to get to the sea.

Seven weeks later, as all the world knows, we went to war. I joined the army in the first week. But I did my best work, I think, before I put on uniform.

"He is safe," he cried. "You cannot follow him. The Black Stone has won."

This old man was more than just a paid spy. Those hooded eyes shone with a deep, burning love for his country. But as the police took him away, I had one more thing to say.

The old man looked at me with wild, crazy eyes.

"Your friend has not won. We put our men on the Ariadne an hour ago."