pausing at the rocky wall of the foundation of the house blasted and
hewn out of the cliff on which it towered above the river. A heavy steel
door in the rock wall barred the way.

Brent whirled the combination and shot the bolts, and the door swung
ponderously open, disclosing a rock-hewn cavern. Three walls of the
cavern were lined with shelves containing inventions of all
kinds--telegraph and telephone instruments, engine models,
railroad-signaling and safety devices, racks of bottles containing
dangerous chemicals and their antidotes--all conceivable manner of
mechanical and scientific paraphernalia. It was literally a Graveyard of
Genius--harboring the ghosts of a thousand inventors' dead hopes.

Brent entered hastily and went directly to a shelf. There he picked up a
model of a motor. He blew the dust from it and examined it approvingly.

Suddenly he saw something that caused him to start. He looked down at
his feet. There was a piece of paper on the floor.

He picked it up and read it, and as he did so he started back,
frightened--then angry. He looked about at the rock-hewn cavern
walls--then read again:

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

Under his breath, Brent swore. Again he looked about the cavern, then
turned hurriedly, picked up the motor, passed out the steel door,
clanged it shut, and locked it.