chase was not a long one. The car which Peter
Ruff had been following was drawn up before a plain, solid-looking
house, unlit and of gloomy appearance. The little lady with the
wonderful eyes was already halfway up the flagged steps. Hastily lifting
the flap and looking behind as they passed, her pursuer saw her open the
door with a latchkey, and disappear. Peter Ruff pulled the check-string
and descended. For several moments he stood and observed the house
into which the lady whom he had been following had disappeared. Then he
turned to the driver.

"I want you to watch that house," he said, "never to take your eyes off
it. When I reappear from it, if I do at all, I shall probably be in a
hurry. Directly you see me be on your box ready to start. A good deal
may depend upon our getting away quickly."

"Very good, sir," the man answered. "How long am I to wait here for
you?"

Peter Ruff's lips twisted into a curious little smile.

"Until two o'clock," he answered. "If I am not out by then, you needn't
bother any more about me. You can return and tell your mistress exactly
what has happened."

"Hadn't I better come and try and get you out, sir?" the man asked.
"Begging your pardon, but her Ladyship told me that there might be queer
doings. I'm a bit useful in a scrap, sir," he added. "I do a bit of
sparring regularly."

Peter Ruff shook his head.

"If there's any scrap at all," he said, "you had better be out of it. Do
as I have said."

The motor car had turned round and disappeared now, and in a few moments
Peter Ruff stood before the door of the house into which the little lady
had disappeared. The problem of entrance was already solved for him. The
door had been left unlatched; only a footstool had been placed against
it inside. Peter Ruff, without hesitation, pushed the door softly open
and entered, replaced the footstool in its former position, and stood
with his back to the wall, in the darkest corner of the hall, looking
around him--listening intently. Nearly opposite the door of a room stood
ajar. It was apparently lit up, but there was no sound of any one moving
inside. Upstairs, in one of the rooms on the first floor, he could hear
light footsteps--a woman's voice humming a song. He listened to the
first few bars, and understanding became easier. Those first few bars
were the opening ones of the Servian national anthem!

With an effort, Peter Ruff concentrated his thoughts upon the immediate
present.