_Indios_ of Matto Grosso,
in Brazil. It drives a man mad, murder mad. It is as if he were
possessed by a devil. His hands first refuse to obey him. His feet
next. And then his body. It is as if a devil had seized hold of his
body and carried it about doing murder with it. A part of the brain is
driven insane, and a man goes about shrieking with the horror of what
crimes his body commits until the poison reaches that portion of his
brain as well. Then he is mad forever. That is what I face, _amigo
mio_. That is why I beg you, I implore you, to kill me or assist me to
the side of the ship so that I may fling myself overboard! The Master
had it administered to me secretly, and demanded treason as the price
of the antidote. He deman--"

* * * * *

Steady and strong, rising from a muttering to a steady roar, the sound
of airplane motors came through the port. Bell started up.

"Hold fast," he snapped savagely. "I'll go get that package when it
lands. Hold fast, I tell you! Fight it!"

He flung out of the cabin and raced up the stairs. The door to the
deck was open. He crowded through a group of passengers who had
discounted the dampness for the sake of a novelty--an airplane far out
at sea--and raced up to the upper deck. The roaring noise was
receding. The siren roared hoarsely. Then the noise came back.

For minutes, then, the ship seemed to play hide-and-seek with the
invisible fliers. The roaring noise overhead circled about, now near,
now seeming very far away. And the siren sent its dismal blasts out
into the grayness all about. Then, for an instant, a swiftly scudding
shadow was visible overhead. It banked steeply and vanished, and
seemed to have turned and come lower when it reappeared a moment
later. It was not distinct, at first. It was merely a silhouette of
darker gray against the all-enveloping mist. But its edges sharpened
and became clear. One could make out struts, an aileron's trailing
edge.

"Got nerve, anyhow," said Bell grimly.

It swept across the ship and disappeared, but the noise of its engines
did not dwindle more than a little. The blast of the siren seemed to
summon it back again. Once more it came in sight, and this time it
dived steeply, flashed across the forecastle deck amid a hideous
uproar, desperately, horribly close to the dangling derrick-cables,
and was gone.

* * * * *

Bell had seen it more clearly than anyone els