"He has been followed, Petrie," he replied, with one of his rare
smiles. "Two C.I.D. men have been watching the house all night!"

This was entirely characteristic of my friend's farseeing methods.

"By the way," I said, "you saw Eltham this morning. He will soon be
convalescent. Where, in heaven's name, can he--"

"Don't be alarmed on his behalf, Petrie," interrupted Smith. "His life
is no longer in danger."

I stared, stupidly.

"No longer in danger!"

"He received, some time yesterday, a letter, written in Chinese, upon
Chinese paper, and enclosed in an ordinary business envelope, having a
typewritten address and bearing a London postmark."

"Well?"

"As nearly as I can render the message in English, it reads:
'Although, because you are a brave man, you would not betray your
correspondent in China, he has been discovered. He was a mandarin, and
as I cannot write the name of a traitor, I may not name him. He was
executed four days ago. I salute you and pray for your speedy
recovery. Fu-Manchu.'"

"Fu-Manchu! But it is almost certainly a trap."