en there is anything in the safe I always carry it about with
me."

"And at other times?"

"Sometimes in a drawer in my writing-table," said Sir Lyster; "but
generally I have it on me."

"When was the document put into the safe?"

"At a quarter to eight to-night, just as the second dressing-gong
was sounding."

"And you yourself put it in, locked the door, and have retained the
key ever since?" Malcolm Sage had exhausted the interest of the
sphinx and was now drawing diagrams with his forefinger upon the
morocco surface of the table.

Sir Lyster nodded.

"I put the key in the pocket of my evening vest when I changed," he
said. "After the other guests had retired, the Prime Minister raised
a point that necessitated reference to the document itself. It was
then I discovered the substitution."

"But for that circumstance the safe would not have been opened until
when?" queried Malcolm Sage.

"Late to-night, when I should have transferred the packet to the
safe in my dressing-room."

"Would you have examined the contents?"

"No. It is my rule to cut adrift from official matters from
dinner-time on Saturday until after breakfast on Monday. It was only
in deference to the Prime Minister's particular wish that we referred
to the document to-night."

"I take it that the rule you mention is known to your guests and
servants?"

"Certainly."

"There is no doubt that it was the document itself that you put in
the safe?"

"None; the Prime Minister and Lord Beamdale saw me do it."

"No doubt whatever," corroborated Mr. Llewellyn John, whilst Lord
Beamdale wagged his head like a mandarin.

"Does anyone else know that it is missing?" asked Malcolm Sage after
a short pause.

Sir Lyster shook his head.

"Only we three; and, of course, the thief," he added.

Malcolm Sage nodded. He had tired of the diagrams, and now sat
stroking the back of his head.

"Has anyone left the house since the discovery; that is, as far as
you know?" he queried at length.

"No one," said Sir Lyster.

"The servants, of course, have access to this room?"

"Yes; but only Walters, my butler, is likely to come here in the
evening, except, of course, my secretary."

"Where does he dine?"

"Miss Blair," corrected Sir Lyster, "always takes her meals in her
own sitting-room, where she works. It is situated at the back of the
house on the ground floor."

Again Malcolm Sage was silent, this time for a longer period.

"So far as yo