I'll git a doctah!" exclaimed the old colored man. "Dey's a phone in
heah."

[Illustration: "Him No Dead!" Rumbled Koku]

Before the physician could be reached, the beneficial effects of the
cool night air had brought the young inventor back to consciousness. At
first he could not recall what had happened and was not a little
astonished to find himself lying on the grass.

"What in the world is the matter, Koku?" he demanded, pressing his hand
to his aching head. "What am I doing out here?"

"Master out, get knockum," said the giant. "We find you on desk. Rad
callum medicine man now."

[Illustration: "What Am I Doing Here?"]

"A doctor? No, I'm all right. Tell him to cancel the call." Tom
managed to struggle to his feet. "I remember now! Some kind of gas must
have been used on me. But I must see to the office. Maybe I've been
robbed."

Leaning heavily on the giant's arm, Tom walked as fast as he could into
the laboratory. At first glance everything seemed to be in order, and to
his relief he found the vault was locked.

[Illustration: The Vault Was Locked]

The young inventor did not know that a key was missing from his ring,
nor, as he twirled the dial of the combination-lock, did he realize that
a slender lever had been severed from below, thus rendering useless the
intricate mechanism.

"Who done dis to you', Massa Tom?" asked Rad.

"Wish I knew. Anyhow, there's been no damage done except to me! My
head's splitting, so I must get to bed. Koku, stay on guard here from
now on until I return from Cuba. And get several of the men to relieve
you. Another thing: I don't want either of you to mention this affair to
anyone. Dad would hear about it and worry."

[Illustration: "Koku, Stay on Guard Here."]

"If I catchum fella I breakum in little bits!" cried Koku fiercely. He
shook the rolling-pin vigorously. "Better him stay 'way fum me!"

Tom awoke the next morning little the worse for his experience. Thanks
to a rugged constitution, he had been able to throw off the ill effects
of the poisonous fumes which had overcome him.

[Illustration: "Better Him Stay 'Way Fum Me!"]

"I can't make it out, Ned," he said as the boys stood watching the
mechanics warm up the engines of the big seaplane. "Nothing is missing.
Whoever did the job didn't even rob me, and I had a good deal of cash in
my wallet."

"Maybe nobody made an attempt on you or your property at all, Tom," Ned
remarked slowly.

"What d'you mean? I