"By jove," Rupert jumped up, "I believe you are right."

"I am sure I am, and in the tree drawn at the side of the picture which you did not observe, there was a white line down the trunk."

"Well," said Rupert pondering, "perhaps whatever is hidden is tied to a string or a chain and is dropped down the trunk of one of the four trees--or perhaps in the stump."

"Not in the stump," said Olivia quickly, "for then the line would be visible, while in the other trees it would be concealed in the thick foliage. I fancy the line must be down the copper beech trunk, as there is but one red bead."

"There is but one tree though--one copper beech you know," said her husband. "I am inclined to think that to make things safer, the hiding place must be in one of the green trees signified by the jade beads. The question is, which tree is it?"

Olivia looked at the fan again, and as she did so started. Rupert also raised his head. They heard the sound of wheels scrunching the gravel outside, and wondered who was arriving so late. The clock pointed to half-past ten. The servants had gone to bed, so Rupert followed by his wife, who was rather nervous, went to the door. When Rupert opened it he found himself facing a tall handsome man in a fur cloak, and wearing a strange hat.

"Good evening," said the stranger in the best of English, "I speak to Mr. Ainsleigh I think, I am the Marquis Lo-Keong."

[CHAPTER XX]

The Mandarin Explains

"I must apologise for this very late visit," said Lo-Keong, when he was conducted to the drawing-room by his surprised host, "but I must explain--"