The whole party was consequently held up on the narrow stairs.  “I’ll go and ask what has become of the key,” Morriston said, making his way past them.

In a minute he returned, presently followed by the butler.

“How is it that this top door is locked, Stent?” he asked.  “And where is the key?”

“I don’t know, sir.  Alfred mentioned this morning that the door was locked and the key taken away; we thought you must have locked it, sir.”

“I?  No, I’ve not been up here since the morning of the ball, when I had those old things brought up from the lower room to be out of the way.”

“Did you lock the door then, sir?”

“No.  Why should I?  I am certain I did not.  Perhaps one of the men did.  Just go and inquire.  And have the key looked for.”

“Very good, sir.”

“This is rather provoking,” Morriston said, as they waited.  “I particularly wanted to show you the view, which should be lovely on a clear day like this.  If we have to wait much longer the light will be going.  Besides, it is quite a quaint old room with a curious recess formed by the bartizan you may have noticed from outside.”

Presently the butler returned accompanied by a footman with several keys.

“We can’t find the right key, sir,” he announced.  “No one seems to have seen it.  Alfred has brought a few like it, thinking one might possibly fit.”

None of them, however, would go into the lock, not even the smallest of them.

“I can’t make it out, sir,” said the man, kneeling to get more effectively to work.  But no key would enter.  The footman at last took a box of matches from his pocket, struck a light and, holding it to the key-hole, peered in.

“Why, the key is in the lock, on the other side, sir,” he said in astonishment.

“Then the door can’t be locked,” Morriston said, pushing it.

The footman rose and pushed too, but the door showed no sign of yielding; it was fastened sure enough.

“This is strange,” Morriston said.  “Hi!  Is any one in there?” he shouted; but no response came.

“Are you sure the key is in the door on the inside?” he asked.

“Certain, sir.  Will you look for yourself, sir?” the man replied, striking another match and holding it so that his master could convince himself.

“No doubt about that,” Morriston declared, as he rose from his scrutiny.  “It is the most extraordinary thing I have ever known.  Can you account for it, Stent?”

The butler shook his head.  “No, sir.  Unless someone is in there now.”

Morriston again shouted, but no answer came.

“I presume there is no way out of the room but this door,” Piercy asked.

“None,” Morriston answered; “except the window, and that is, I should say, quite eighty feet from the ground; eh, Mr. Gifford?”

“A sheer drop of quite that distance,” he answered.