Spurlin's voice shattered the silence. "Here we are." Now he was flashing a tiny light upon a massive metal door. And Jim's heart leaped, for he saw it as a metal new, and yet not new to him. It was the same dull, greenish-gray metal as the piece Kaarji had given him. Jim passed his fingers lightly across it to make sure, but said nothing.
For more than any of these things he was thinking of a bent and shrivelled old Martian named Bhruulo, who had chuckled with a secret evil glee.
The door swung ponderously open. They stepped into a huge oval room, and many men came hurrying toward them. The walls of this room, Jim noticed, were of the same peculiar metal.
"Introductions later," Spurlin said, as the men came crowding around. "Right now I want you newcomers to see the work we're engaged in here. You look like the sort who can help us in the job."
He led them to another room where a long, skeletal shape was under construction. It rested on curved cradles, pointing upward. Only a few outer plates had as yet been put into place, plates of the same strange metal Jim identified with everything here.
"A spaceship!" he exclaimed unbelievingly. "But—why a spacer here, so far beneath Mars' surface?"
"A spacer it is, Jim Landor. One such as you never saw before, and it's being built under conditions such as you cannot imagine. We have to mine and fashion the metal in the few tiny furnaces we have here, and it's inconceivably slow due to the scarcity and crudeness of tools. We've been at work on this one spacer for three years.
"As for this new metal, it's to be found here in huge deposits. In some ways it's like radite, it might even be radite, strangely changed through the centuries by those peculiar green radiations. Anyway, it's amazingly light and tough, almost expansive under fuel pressure and it's going to revolutionize spacer construction if we can only get any from here and make it known!"
"But how, man? How do you propose—"
"To get the spacer out of here?" Spurlin smiled confidently. "In one super blast we're going to hurl through this roof to the city above, and through that cavern roof onto the surface of Mars. I'm fully convinced this metal is capable of withstanding it. We're building a double hull. And we have enough fuel hoarded here to take us clear to Earth if we wish."