one but Joseph could have concealed anything—you told us in your narrative how you had turned Joseph out when you arrived with the doctor—my suspicions all changed to certainties, especially as the attempt was made on the first night upon which the nurse was absent, showing that the intruder was well acquainted with the ways of the house.’

‘How blind I have been!’

‘The facts of the case, as far as I have worked them out, are these: This Joseph Harrison entered the office through the Charles Street door, and knowing his way he walked straight into your room the instant after you left it. Finding no one there he promptly rang the bell, and at the instant that he did so his eyes caught the paper upon the table. A glance showed him that chance had put in his way a State document of immense value, and in a flash he had thrust it into his pocket and was gone. A few minutes elapsed, as you remember, before the sleepy commissionaire drew your attention to the bell, and those were just enough to give the thief time to make his escape.

‘He made his way to Woking by the first train, and, having examined his booty and assured himself that it really was of immense value, he concealed it in what he thought was a very safe place, with the intention of taking it out again in a day or two, and carrying it to the French Embassy, or wherever he thought that a long price was to be had. Then came your sudden return. He, without a moment’s warning, was bundled out of his room, and from that time onwards there were always at least two of you there to prevent him from regaining his treasure. The situation to him must have been a maddening one. But at last he thought he saw his chance. He tried to steal in, but was baffled by your wakefulness. You may remember that you did not take your usual draught that night.’

‘I remember.’

‘I fancy that he had taken steps to make that draught efficacious, and that he quite relied upon your being unconscious. Of course, I understood that he would repeat the attempt whenever it could be done with safety. Your leaving the room gave him the chance he wanted. I kept Miss Harrison in it all day, so that he might not anticipate us. Then, having given him the idea that the coast was clear, I kept guard as I have described. I already knew that the papers were probably in the room, but I had no desire to rip up all the planking and skirting in search of them. I let him take them, therefore, from the hiding- place, and so saved myself an infinity of trouble. Is there any other point which I can make clear?’

‘Why did he try the window on the first occasion,’ I asked, ‘when he might have entered by the door?’

‘In reaching the door he would have to pass seven bedrooms. On the other hand, he could get out on to the lawn with ease. Anything else?’

‘You do not think,’ asked Phelps, ‘that he had any murderous intention? The knife was only meant as a tool.’

‘It may be so,’ answered Holmes, shrugging his shoulders. ‘I can only say for certain that Mr Joseph Harrison is a gentleman to whose mercy I should be extremely unwilling to trust.’