“Who else but you could have murdered him?” cried Lemoine. “Tell me that!”

The last word died on his lips, as a shrill whistle sounded from the terrace outside. Anthony sprang up, all his assumed nonchalance laid aside.

“You ask me who murdered Prince Michael?” he cried. “I won’t tell you⁠—I’ll show you. That whistle was the signal I’ve been waiting for. The murderer of Prince Michael is in the library now.”

He sprang out through the window, and the others followed him as he led the way round the terrace, until they came to the library window. He pushed the window, and it yielded to his touch.

Very softly he held aside the thick velvet curtain, so that they could look into the room.

Standing by the bookcase was a dark figure, hurriedly pulling out and replacing volumes, so absorbed in the task that no outside sound was heeded.