thers were--gone? It had shown no marks of violence. She must have
died of fear. No, her face had seemed too calm and peaceful for that.
Had she chosen easy death by some poison, rather than that other
dreadful fate? Had her body been put in the chest to protect it, and
the poison arrested decomposition?

Thad was still studying the picture, thoughtfully and sadly, when the
dog, which had been silent, suddenly growled again, and retreated from
the door, toward the corner of the room.

The invisible monster had returned. Thad heard its claws scratching
across the door again. And he heard another dreadful sound--not the
long, shrill scream that had so grated on his nerves before, but a
short, sharp coughing or barking, a series of shrill, indescribable
notes that could have been made by no beast he knew.

* * * * *

The decision to open the door cost a huge effort of Thad's will.

For hours he had waited, thinking desperately. And the thing outside
the door had waited as patiently, scratching upon it from time to
time, uttering those dreadful, shrill coughing cries.

Sooner or later, he would have to face the monster. Even if he could
escape from the room and avoid it for a time, he would have to meet it
in the end. And it might creep upon him while he slept.

To be sure, the issue of the combat was extremely doubtful. The
monster, apparently, had succeeded in killing every man upon the
flier, even though some of them had been armed. It must be large and
very ferocious.

But Thad was not without hope. He still wore his Osprey-suit. The
heavy fabric, made of metal wires impregnated with a tough, elastic
composition, should afford considerable protection against the thing.

The welding arc, intended to fuse refractive meteoric iron, would be
no mean weapon, at close quarters. And the quarters would be close.

If only he could find some way to make the thing visible!

Paint, or something of the kind, would stick to its skin.... His eyes,
searching the room, caught the jar of face powder on the dressing
table. Dash that over it! It ought to stick enough to make the outline
visible.

So, at last, holding the powder ready in one hand, he waited until a
time when the pressure upon the door had just relaxed, and he knew the
monster was waiting outside. Swiftly, he opened the door....

* * * * *

Thad had partially overcome the instinctive horror that th