ale. "You will have to keep
close to me after to-morrow. Make yourself at home here until I come
back."

"One moment," said Homo, as Beale rose and gathered up his hat and
gloves to depart. "Before you go I want you to understand clearly that I
am taking on this job because it offers me a chance that I haven't had
since I fell from grace, if you will excuse the _cliche_."

"That I understand," said Beale.

"I may be doing you a very bad turn."

"I'll take that risk," said Beale.

"On your own head be it," said Homo, his hard face creased in a
fleeting smile.

Beale's car was waiting, but his departure was unexpectedly delayed. As
he passed down the stairs into the vestibule he saw a stranger standing
near the door reading the enamelled name-plates affixed to the wall.
Something in his appearance arrested Beale. The man was well dressed in
the sense that his clothes were new and well cut, but the pattern of the
cloth, no less than the startling yellowness of the boots and that
unmistakable sign-manual of the foreigner, the shape and colour of the
cravat, stamped him as being neither American nor British.

"Can I be of any assistance?" asked Beale. "Are you looking for
somebody?"

The visitor turned a pink face to him.

"You are very good," he said with the faint trace of an accent. "I
understand that Doctor van Heerden lives here?"

"Yes, he lives here," said Beale, "but I am afraid he is not at home."

He thought it might be a patient or a summons to a patient.

"Not at home?" The man's face fell. "But how unfortunate! Could you tell
me where I can find him, my business is immediate and I have come a long
way."

From Germany, guessed Beale. The mail train was due at Charing Cross
half an hour before.

"I am a friend of Doctor van Heerden and possibly I can assist you. Is
the business very important? Does it concern," he hesitated, "the Green
Rust?"

He spoke the last sentence in German and the man started and looked at
him with mingled suspicion and uncertainty.

"It is a matter of the greatest importance," he repeated, "it is of
vital importance."

He spoke in German.

"About the Green Rust?" asked Beale, in the same language.

"I do not know anything of the Green Rust," said the man hurriedly. "I
am merely the bearer of a communication which is of the greatest
importance." He repeated the words--"the greatest importance."

"If you give me the letter," said Beale, "I will see that it is sent