"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 be trained upon the other side of that door by the aliens. They might be walking into a trap. He half expected one of those disconcerting thought answers from Dalgard. But the scout was playing safe--nothing must upset the stranger. Confronted by what had to be done, he might be influenced into acting for them. So Dalgard strode softly ahead, apparently not interested in Raf. One of the mermen worked at the door, using the point of his spear as a lever. Here again was a vista of machinery. But these machines were alive; a faint hum came from their casings. The mermen scattered, taking cover, a move copied by the two humans.