sure that the door to the library was bolted.

As he did so he did not see his secretary, Zita, watching in the hall,
for the footsteps of Locke, approaching, had caught her quick ear and
she had fled.

"Locke!" called Brent, hearing his laboratory, manager. "Under no
circumstances allow me to be disturbed to-night."

"Very well, sir," responded Locke.

Just then the light step of Eva was heard on the stairs.

"What's the matter, father?" she asked, still upset by the events of the
afternoon. "Is there anything wrong?"

"No, my dear, nothing," hastily replied Brent. "In the morning I shall
have something to say to you. Now run along like a good girl."

Dutifully Eva turned. Brent watched her out of sight. Then with a keen
look at Locke he pulled out a paper from his pocket and handed it to the
young scientist, who read:

BRENT,--This is my last warning. If you persist in your course you
will be struck down by the Madagascar madness.
Q.

Locke looked up from the scrawl in alarmed perplexity.

"What does this mean?" he queried.