mall parties of mermen broke from the regiment to follow
certain ones, leaving without orders or farewells. At the fifth of
these Dalgard touched Raf's arm and drew him aside.

"This is our way." Tensely the scout waited. If the stranger refused,
then the one plan the scout had formed during the past half-hour would
fail. He still held to the hope that Raf, with what Raf carried, could
succeed in the only project which would mean, perhaps not his safety
nor the safety of the tribe he now marched among, but the eventual
safety of Astra itself, the safety of all the harmless people of the
sea, the little creatures of the grass and the sky, of his own land at
Homeport. He would have to force Raf into action if need be. He did
not use the mind touch; he knew now the unspoken resentment which
followed that. If it became necessary--Dalgard's hands balled into
fists--he would strike down the stranger--take from him--Swiftly he
turned his thoughts from that. It might be easy, now that he had
established mental contact with this off-worlder, for the other to
pick up a thought as vivid as that.

But luckily Raf obediently turned into the side passage with the six
mermen who were to attack at this particular point. The way grew
narrower until they crept on hands and knees between rough walls which
were not of the same construction as the larger tunnels. The smaller
mermen had no difficulty in getting through, but twice Raf's equipment
belt caught on projections and he had to fight his way free.

They crawled one by one into a ventilation shaft much like the one he
had climbed at the Center. Dalgard's whisper reached him.

"We are now in the building which houses their sky ship."

"I know that one," Raf returned almost eagerly, glad at last to be
back so close to familiar territory. He climbed up the hand-and
footholds the sea-monster lamp disclosed, wishing the mermen ahead
would speed up.

The grille at the head of the shaft had been removed, and the invaders
arose one by one into a dim and dusty place of motionless machinery,
which, by all tangible evidence, had not been entered for some time.
But the cautious manner in which the sea people strung out to approach
the far door argued that the same might not be true beyond.

For the first time Raf noticed that his human companion now held one
of the knives of the merpeople, and he drew his stun gun. But he could
not forget the flame-throwers which might at that very moment