it was to the rattling of the door. Murray stirred.
The light was even weaker than before.

"If they offer you a drink, drink hearty!" Murray muttered, sitting
up. "I've got an idea it's going to be a hard day."

But they were not offered any water. Instead they were again conducted
before Scar Balta, who looked at them morosely. At last he remarked
gruffly:

"If you tin sojers weren't so cursed stubborn, you could get yourself
a nice berth in the Martian army. Ever consider that?"

"Talk sense!" Sime said contemptously. "If I threw down the service
how could you trust me?"

"That'd be easy," Balta rejoined. "Once the I. F. P. finds out you
joined us you'd have to stick with us to save your skin."

He laughed at his prisoners' look of surprise.

"Come, come!" he bantered. "You didn't think that I was ignorant of
your purpose here? You, Murray; your spying was excellent, I'll admit.
You were the first to give away certain plans of ours. Well, well! We
don't hold that against you. Wheels within wheels, eh? It would
perhaps astonish certain braided gentleman of our high command to
learn that I, a mere colonel, control their destinies. As our
ancestors would say, it's dog eat dog.

"Now, how about it? I can make a place for you in my organization. It
seems to run to secret service, oddly enough. You will be rewarded far
beyond anything you could expect in your present career of chasing
petty crooks from Mercury to Pluto and back again."

"Is that all?" Murray asked softly, with a bearded grin.

"Oh no. You will turn over to me all the information you can about the
I. F. P. helio code. You will name and describe to me each and every
plainclothes operative of the service--and you should have an
extensive acquaintance."

"Before you answer," Murray said quietly at Sime's side, "let me
suggest that you consider what's in store for us--or you--if you don't
take up this offer."

"Why, you--" Sime whirled in astonished fury upon his companion.
"Didn't you--"

* * * * *

But he did not complete his reference to last night's surreptitious
conversation. It seemed that he saw the merest ghost of a flicker in
Murray's left eye.

"--Didn't you say you'd stick no matter what they did?" he finished
lamely.

Murray hung his head.

"I'm getting along," he muttered. "Not as young as I used to be. This
life is getting me nowhere. Why be a fool? Come along with me!"

"Why, you dirty, doub