unknown enemy was running swiftly
down the corridor, the sucking patter of his feet giving more evidence
of his Ganymedan origin. Pemberton sprang to the door, thrust it open
just in time to see a dark shape disappearing around a bend in the
corridor. There was no use of pursuit; the passageway ended in a spray
of smaller corridors, from which ambush would be absurdly easy.

* * * * *

HE glanced swiftly around. The corridor was empty, silent in the dim,
diffused light. The motley passengers were all sound asleep; no one
had been disturbed by the fracas. Earthmen, green-faced Martians,
fish-scaled Venusians, spatulate Ganymedans and homeward-bound
Callistans, all reposing through the sleep-period in anticipation of
an early landing in Callisto.

All were asleep, that is, but one. That brought Pemberton back to the
problem of his mysterious assailant. Why had this Ganymedan tried to
whiff him out of existence? Grant frowned. No one on board knew of his
mission, not even the captain. On the passenger list he was merely
Dirk Halliday, an inconspicuous commercial traveler for Interspace
Products. Yet someone had manifestly penetrated his disguise and was
eager to remove him from the path of whatever deviltry was up. Who?

Grant gave a little start, then swore softly. Of course! Why hadn't he
thought of it before! The scene came back to him, complete in every
detail, as though he were once more back on Earth, in the small,
simply furnished office of the Interplanetary Secret Service.

The Chief of the Service was glancing up at him keenly. Beside him was
a tall, powerfully shouldered Ganymedan, Miro, Inspector for Ganymede.
Grant looked at him with a faint distaste as he sat there, drumming on
the arm of his chair with his spatulate fingers, his soft-suction
padded hoofs curled queerly under the seat. There was something
furtive, too, about the red lidless eyes that shifted with quick
unwinking movements.

* * * * *

But then, Pemberton had small use for the entire tribe of Ganymedans.
Damned pirates, that's all they were. It was not many years back since
they had been the scourge of the solar system, harrying spatial
commerce with their swift piratical fliers, burning and slaying for
the mere lust of it.

That is, until an armada of Earth space-fliers had broken their power
in one great battle. The stricken corsairs were compelled to disgorge
their accu