ow and then
turning to scan the desert for the returning Phil.

It was then, startlingly sudden, that there cracked through the velvet
night the faint, distant sound of a gun. And it came from the
direction of the water-hole.

Sue's face went white, and she trembled. Without a word her father
stepped out of the borer and looked at her.

"That was a gun!" he said. "Phil didn't have one with him, did he?"

"No," Sue whispered. "And--why, there's nobody within miles of here!"

The two looked at each other with alarm and wonder. Then, from one of
the broken patches of scrub that ringed the space in which the borer
stood, came a mocking voice.

"Ah, you're mistaken, Sue," it affirmed. "But that was a gun."

David Guinness jerked around, as did his daughter. The man who had
spoken stood only ten yards away, clearly outlined in the bright
moonlight--a tall, well-built man, standing quite at ease, surveying
them pleasantly. His smile did not change when old Guinness cried:

"Quade! James Quade!"

The man nodded and came slowly forward. He might have been considered
handsome, had it not been for his thin, mocking lips and a swarthy
complexion.

"What are you doing here?" demanded Guinness angrily. "And what do you
mean--'it was a gun?' Have you--"

"Easy, easy--one thing at a time," said Quade, still smiling. "About
the gun--well, your young friend Holmes said, he'd be right back, but
I--I'm afraid he won't be."

* * * * *

Sue Guinness's lips formed a frightened word:

"Why?"

Quade made a short movement with his left hand, as is brushing the
query aside. "Let's talk about something more pleasant," he said, and
looked back at the professor. "The radium, and your borer, for
instance. I hear you're all ready to go down."

David Guinness gasped. "How did you know--?" he began, but a surge of
anger choked him, and his fists clenched. He stepped forward. But
something came to life in James Quade's right hand and pointed
menacingly at him. It was the stubby black shape of an automatic.

"Keep back, you old fool!" Quade said harshly. "I don't want to have
to shoot you!"

Unwillingly, Guinness came to a stop. "What have you done with young
Holmes?" he demanded.

"Never mind about him now," said Quade, smiling again. "Perhaps I'll
explain later. At the moment there's something much more interesting
to do. Possibly you'll be surprised to hear it, but we're all going to
take a littl