of dials stood neglected. A score of dials and switches were
here, governing the magnetism of different areas of the ship. There
should have been a night operator, but he was gone.

Then we saw him lying nearby, sprawled face down on the floor! In the
silence and dim lurid glow of the fluorescent tubes, we stood holding
our breaths, peering and listening. No one here.

The guard was not dead. He lay unconscious from a blow on the head. A
brawny fellow. We had him revived in a few moments. A broadcast flash of
the call-buzz brought Dr. Frank in haste from the chart-room.

"What's the matter?"

We pointed at the unconscious man. "Someone was here," I said hastily.
"Experimenting with the magnetic switches. Evidently unfamiliar with
them--pulling one or another to test their workings and so see the
reactions on the dials."

We told him what had happened to Snap in the upper corridor.

Dr. Frank revived the guard in a moment. He was no worse off for the
episode, save a lump on his head, and a nasty headache.

But he had little to tell us. He had heard a step. Saw nothing--and
then had been struck on the head, by some invisible assailant.

* * * * *

We left him nursing his head, sitting belligerent at his post. Armed now
with my heat-ray cylinder which I loaned him.

"Strange doings this voyage," he told us. "All the crew knows it--all
been talkin' about it. I stick it out now, but when we get back home I'm
done with this star travelin'. I belong on the sea anyway. A good old
freighter is all right for me."

We hurried back to the upper level. We would indeed have to plan
something at this chart-room conference. This was the first tangible
attack our adversaries had made.

We were on the passenger deck headed for the chart-room when all three
of us stopped short, frozen with horror. Through the silent passenger
quarters a scream rang out! A girl's shuddering, gasping scream. Terror
in it. Horror. Or a scream of agony. In the silence of the dully
vibrating ship it was utterly horrible. It lasted an instant--a single
long scream; then was abruptly stilled.

And with blood pounding my temples and rushing like ice through my
veins, I recognized it.

Anita!

CHAPTER IX

_The Murder in A 22_

"Good God, what was that?" Dr. Frank's face had gone white in the
starlight. Snap stood like a statue of horror.

The deck here was patched as always, silver radiance from the deck
por