them the slip," he
muttered. "He ought to have been under close surveillance from the moment
he set foot in New York. What's that?" he added, turning to the door.

His servant entered, bearing a note.

"This was left a few minutes ago, sir," he announced, "by a messenger boy.
There was no answer required."

The man retired and Quest unfolded the sheet of paper. His expression
suddenly changed.

"Listen!" he exclaimed.

To Sanford Quest.

Gather your people in Professor Ashleigh's library at ten
o'clock to-night. I will be there and tell you my whole story.

JOHN CRAIG.

The Professor sat for a moment speechless.

"Then he meant it, after all!" he exclaimed at last.

"Seems like it," Quest admitted. "I'll just telephone to French."

The Professor rose to his feet, knocked the ash from his cigar, struggled
into his coat, and took up his hat. Then he waited until Quest had
completed his conversation. The latter's face had grown grave and puzzled.
It was obvious that he was receiving information of some importance. He
put down the instrument at last with a curt word of farewell.

"Let me send a couple of men up with you, Professor," he begged. "You
don't want to run any risk of having Craig there before we arrive."

The Professor smiled.

"My friend," he said, "it is seldom in my life that I have had to have
recourse to physical violence, but I flatter myself that there is no man
who would do me any harm. We will meet, then, at my house. You will bring
the young ladies?"

"Sure!" Quest replied. "I am just sending word up to them now."

The Professor moved towards the door.

"If only this may prove to be the end!" he sighed.

* * * * *

Quest spent the next hour or so in restless deliberations. There were
still many things which puzzled him. At about a quarter past nine Lenora
and Laura arrived, dressed for their expedition. Quest threw open the
window and looked out across the city. A yellowish haze which, accompanied
by a sulphurous heat, had been brooding over the city all day long, had
suddenly increased in density. The air was stifling.

"I'm afraid we are in for a bad thunderstorm, girls," Quest remarked.

Laura laughed.

"Who cares? The automobile's there, Mr. Quest."

"Let's go, then," he replied.

They descended into the street and drove to the Professor's house in
silence. Even Laura was feeling the strain of these last hours of anxiety.