“What did you do next?”

“By that time, the alarm had been raised and Mr. Forbes of the Metropolitan Police had arrived on the scene. He also suspected Mrs. Tanner. Why had she hurried out of the building? Mrs. Tanner couldn’t explain it, except that it was the time she always went home. Forbes and I hired a cab and within half an hour, we were at the Tanners’ house in Brixton.

“Their daughter answered the door and told us her mother hadn’t yet returned. We waited in the front room and, about ten minutes later, there was a knock on the door. I wish we’d opened it ourselves, but the daughter got there first and said, ‘Mother, there are two men waiting to see you.’ There was a sound of running feet in the passage. Forbes flung open the door, and we ran into the kitchen. Mrs. Tanner was in there, staring at us defiantly. Then she recognized me, and her expression changed to surprise. ‘Why, if it isn’t Mr. Phelps from the office! What are you doing here?’

“‘Why did you just run in here, madam?’ asked Forbes.

“‘I thought you were the moneylenders,’ she replied. ‘We’ve had some trouble paying back our loan.’

“Forbes said to her: ‘We have reason to believe that you have taken a paper of importance from the Foreign Office and that you ran in here to get rid of it.’ We looked around the kitchen, checking the ashes in the fireplace, but found nothing. Then we took the protesting Mrs. Tanner back to the police station where she was searched by a matron, who found nothing.

“This was the moment, Mr. Holmes, when the full horror of my situation first dawned on me. Until then, I’d been so busy rushing about and so confident I’d find the treaty, I hadn’t thought about what would happen if I didn’t. Now I felt myself start to crumble inside. Watson can tell you how nervous and sensitive I was at school—well, I still am.

“I thought how I’d brought shame on my uncle and jeopardized the security of this country. It didn’t matter that it was an accident. My career was in ruins. As these thoughts went through my head, I sat down there in the police station and cried and cried. Eventually, a policeman saw me onto the train and back here to Woking. By the time I got home, I was, I’m afraid to say, quite out of my mind.”

Percy Phelps managed another weak smile. “That’s almost the end of my story, Mr. Holmes. When I got here, my doctor, Dr. Ferrier, took charge of my health. He decided this room should be my sick room, so Joseph had to move out. I have been lying here for the past nine weeks. During the day, my lovely Annie takes care of me, and at night, a hired nurse looks after me.

“Slowly, the madness has lifted and my mind has become clear again. As soon as I felt better, I contacted Mr. Forbes. He told me they’ve made no progress on the case. They’ve investigated the Tanners and have been following Charles Gorot, my colleague who stayed behind that night to finish some work. They’ve found nothing to blame any of them. Mr. Holmes, you’re my final hope. If you can’t help me, I’m finished.”

Phelps sank back on his cushions, overcome with emotion.

Annie gave him a teaspoon of soothing medicine. “Is there any chance you can help, Mr. Holmes?” she asked.

“It’s a complicated case,” Holmes replied, “but I promise to give it my fullest attention.”

“I won’t be able to sleep until you return,” said Phelps.

On the train back to London, Holmes and I discussed the case. “The first question to ask when trying to solve a crime like this is who benefits from it,” said Holmes.

“The French government would benefit from stealing the treaty, and so would anyone who might want to sell it to them,” I said.

“That’s true,” agreed Holmes. “And then there’s Lord Holdhurst.”

“Lord Holdhurst?” I exclaimed. “He’d be the last person to want the French to get hold of it.”

“Maybe. But it’s possible he wouldn’t be sorry to see it accidentally destroyed. Let’s see if we can find any clues when we interview his lordship later today. Meanwhile, I have already sent out inquiries.”

“Already? But we’ve only just left Percy’s house.”

“I sent messages from Woking Station to every evening newspaper in London. This advertisement will appear in all of them.”

He handed me a sheet torn from a notebook. On it was scribbled in pencil:

10 reward. The number of the cab that dropped someone at the Foreign Office on Charles Street at quarter to ten on the evening of May 23.

“Are you sure the thief came in a cab?” I asked.

“Reasonably. If Phelps is right and there’s no hiding place in the room or corridors, then the thief must have come from outside. On such a wet night, he’d have left damp footmarks on the floor, but there weren’t any, so a cab must have brought him to the door.”

“I see what you mean.”

“I’ve also been thinking about that bell,” said Holmes. “Why should it ring? Did the thief do it to show off? Did he ring it by accident? Or was it rung by someone else who wanted to stop the crime?” Holmes sank back in his seat in deep thought. If he found any answers to these questions, he didn’t share them with me.

We arrived at Waterloo Station at 3:20 PM. After a quick lunch at the station café, we went to Scotland Yard, the headquarters of the Metropolitan Police.

Mr. Forbes, the detective, a small man with sharp features, was waiting for us. “I know your methods, Mr. Holmes,” he said stiffly. “You use all the information the police give you and then take credit for solving the case.”

“On the contrary,” said Holmes. “Out of my last fifty-three cases, my name has only appeared in four. I don’t blame you for not knowing this because you’re young and inexperienced. But if you want to do well in your career, I suggest you work with me, not against me.”

Hearing this, Forbes’s attitude changed completely. “In that case,” he said, “I’d be grateful for any help you can provide. The truth is, we’re stuck.”

“Did you investigate Phelps’s colleague Charles Gorot, who stayed late at the office on the night the treaty was stolen?”

“Yes, we’ve been following him these past nine weeks. He has French ancestry, which made us a bit suspicious, but we’ve found no evidence against him.”

“What about the Tanners? I understand they had some problems with moneylenders.”

“They paid off their debts.”

“Where did the money come from?”

“Mr. Tanner paid it out of his pension. They’ve shown no signs of sudden wealth.”

“Did she say why she answered Phelps’s call when he rang the bell?”

“Her husband was tired, she claimed.”

“That matches up with Phelps’s story,” I pointed out. “He said he found him asleep in his chair.”

“Did you ask her why she was in such a hurry that night?” asked Holmes.

“She was late and wanted to get home.”

“Yet you left twenty minutes after her and got there before her.”

“She said that’s the difference between a bus and a hansom cab.”

“And why did she rush into the kitchen when she got home?”

“Because she had the money there to pay off the moneylenders.”

“It seems she has an answer for everything,” sighed Holmes. “What else have you done?”

“That’s all, Mr. Holmes. We have nothing else to go on. Do you have any ideas? Why did that bell ring?”

Holmes chose not to answer this. “Thank you, Mr. Forbes, for all you’ve told me. If I can find the thief, I certainly will. Come along, Watson.”

“Where are we going now?” I asked as we left Scotland Yard.

“To interview Lord Holdhurst,” replied Holmes.

We found Lord Holdhurst in his office on Downing Street. Holmes gave his card to the doorman, and we were soon shown upstairs. The Foreign Minister greeted us politely. He was an impressive man—tall and straight-backed with silver hair and a gracious smile.

“Your name is well-known to me, Mr. Holmes,” he said. “I think I can guess why you’re here.”

We sat while he remained standing.

“My client is Percy Phelps,” said Holmes.

“Ah, my poor, unfortunate nephew,” sighed Holdhurst. “You understand why I cannot protect him—people will say it’s only because he’s family. I fear this incident will harm his career.”

“What if the treaty is found?” Holmes asked.

“That would be different. How can I help you, Mr. Holmes?”

“Lord Holdhurst, did you tell Mr. Phelps to copy the treaty in this room?” Holmes asked.

“Yes, I did.”

“Then you weren’t overheard?”

“No, I wasn’t.”

“Did you tell anyone you planned to have the treaty copied?”

“No, I didn’t.”

“Since nobody knew about the copying, it must have been a crime of opportunity. The thief saw his chance and took it. Do you agree?”

“It’s possible,” Holdhurst replied.

Holmes thought for a moment. “There’s something else I wanted to ask you, Lord Holdhurst. I understand that if the French discovered this treaty, it would have serious consequences.”

“Very serious.”

“And have these consequences happened yet?”

“No, not yet.”

“So we can assume the French don’t know about the treaty?”

“That seems to be the case.”

“Is there any other reason why the thief might have stolen it?”

Lord Holdhurst shrugged. “I don’t think he took it to hang on his wall. I’m sure he’s offered it to the French and is waiting for a better price. If he waits too long, he’ll get nothing because the treaty will be made public in a few months.”

“It’s possible,” suggested Holmes, “that the thief became suddenly ill.”

“A mental breakdown, perhaps,” said Holdhurst, glancing at Holmes.

“I didn’t say that,” replied Holmes calmly.

As we left Downing Street, Holmes remarked, “Lord Holdhurst is a good man, but he’s trying to keep up appearances. I don’t think he’s as wealthy as he seems. Did you notice his boots had been resoled? A man like that might be tempted by a chance to make quick money.”

He left me with this thought and said no more about it.

Before we parted, he asked if I would go with him to Woking the next morning. I agreed immediately, sensing we were close to solving the case and not wanting to miss it.

I met Holmes at the station the next morning, and we took the same early train to Woking. He had received no response to his advertisement and no new information about the case. My friend’s face can be very expressionless sometimes, and I couldn’t tell if he felt hopeful or gloomy about solving this mystery.