for which Ward had
been heading, wasn't kept for fun. Besides, Caron was too smart to have
only one string to his bow.

Shouts, the spatter of shots around them. The narrow trail loomed above.
Gray sent the girl scrambling up.

The sun burst up over the high peaks, leaving the black shadow of the
valley still untouched. Caron's ship roared off. But six of its crew
came after Gray and Jill Moulton.

* * * * *

The chill dark of the tunnel mouth swallowed them. Keeping right to
avoid the great copper posts that held the cables, strung through holes
drilled in the solid rock of the gallery's outer wall, Gray urged the
girl along.

The cleft his hand was searching for opened. Drawing the girl inside,
around a jutting shoulder, he stopped, listening.

Footsteps echoed outside, grew louder, swept by. There was no light. But
the steps were too sure to have been made in the dark.

"Infra-red torches and goggles," Gray said tersely, "You see, but your
quarry doesn't. Useful gadget. Come on."

"But where? What are you going to do?"

"Escape, girl. Remember? They smashed my ship. But there must be another
one on Mercury. I'm going to find it."

"I don't understand."

"You probably never will. Here's where I leave you. That Martian Galahad
will be along any minute. He'll take you home."

Her voice came soft and puzzled through the dark.

"I don't understand you, Gray. You wouldn't risk my life. Yet you're
turning me loose, knowing that I might save you, knowing that I'll hunt
you down if I can. I thought you were a hardened cynic."

"What makes you think I'm not?"

"If you were, you'd have kicked me out the waste tubs of the ship and
gone on. You'd never have turned back."

"I told you," he said roughly, "I don't kill women." He turned away, but
her harsh chuckle followed him.

"You're a fool, Gray. You've lost truth--and you aren't even true to
your lie."

He paused, in swift anger. Voices the sound of running men, came up from
the path. He broke into a silent run, following the dying echoes of
Caron's men.

"Run, Gray!" cried Jill. "Because we're coming after you!"

The tunnels, ancient blowholes for the volcanic gases that had tortured
Mercury with the raising of the titanic mountains, sprawled in a
labyrinthine network through those same vast peaks. Only the galleries
lying next the valleys had been explored. Man's habitation on Mercury
had been too short.

Gray could