ent breath noisily, and inhaled deeply.

Eyes smarting and head reeling, he saw Ulana through a haze of dancing
smoke wisps he knew were illusory. She was safe, thank God! They were
on the moving platform then, on the return side, and his strength was
returning. Narrow escape, he'd had, from that lung-rotting gas. Ulana
smiled happily when his vision cleared.

* * * * *

The speeding platform carried them swiftly toward the lift that had
brought them down. What if the lift would not operate? This Denari
might well have shut off the power or even returned the cage to the
upper end of the shaft.

"Boy, oh boy," Tommy was saying, "you sure did gum up the works. Know
what happened?"

"Plenty, from the look of things," Blaine smiled grimly.

"I'll say. You cut down the dry soil ratio a third. Not sure of the
exact reaction, but the expansion was too rapid. Explosion followed
before the air could be driven from the tube. I'll bet the big cannon
was wrecked somewhere overhead. Boy, what a blast!"

As if the last sentence were a prophecy, there came a terrific jar that
twisted the platform violently from under them. They were thrown
headlong and an awe-inspiring rumbling came up from the vitals of
Antrid. An earthquake! The tortured satellite could not withstand the
strains set up by the tremendous reactive force of the rocket-tube. The
lights snuffed out and the platform came to a grinding stop. One of the
underground power plants was out of commission and they were trapped
here in the stifling darkness.

"Nice fix we're in now!" Tommy grunted where he had fallen.

Blaine, having located Ulana, was relieved to find that she was
unharmed. "Yes," he said slowly; "but there's one thing sure: they
can't follow us here unless they walk."

"Why can't we walk?" Ulana asked with forced cheerfulness. "It isn't
far now."

"Oh, we can walk all right; we'll have to. And here's hoping we get
somewhere." Tommy, at least, was undaunted so far.

* * * * *

It was their only chance now. Blaine held fast to the girl as they felt
their way along the smooth tunnel wall, and Tom Farley, behind them
there in the darkness, kept up a running fire of small talk that was
utterly irrelevant. Nothing could keep that Irishman down.

After what seemed like miles of steady plodding they glimpsed a light
ahead. They quickened their pace. It was the open door at