within it that all that
remained of either was a heap of diamond and amber dust. The only
things left intact were the Silver Belt and the metal collar.

Powell snatched up the Belt and extracted the small piece of paper
that had been firmly tucked into its coils. Hurriedly written in
pencil upon the paper was a message in a handwriting familiar to
both Powell and Marlowe:

Help! I am held prisoner in the Cave of Blue Flames!
--Joan.

"Larry, Joan must still be alive over there in Arret!" There was new
hope in Benjamin Marlowe's voice.

"Yes, alive and held captive by whatever monstrosities may inhabit
that unknown plane," Powell agreed grimly. "There's only one way in
which we can possibly rescue her now. That is for you to send me
into Arret with a reserve Belt for Joan. I'll be ready to start as
soon as I get a couple of automatic pistols that I have up in my
room. It's a sure thing that I'll need them over there in Arret."

* * * * *

Five minutes later Powell stood ready and waiting upon the
floor-plate in the focus of the big atomic projector, with the
central lens of the apparatus levelled down upon him like a huge
searchlight. Around Powell's waist were strapped two Silver Belts,
and a cartridge belt with a holstered .45-calibre automatic on
either side. His wrist-watch was synchronized to the second with
Benjamin Marlowe's watch.

"Joan's twelve-hour time limit in Arret will expire at one o'clock
tomorrow morning." Powell reminded Marlowe. "That gives me nearly
six hours in which to find her and equip her with a Silver Belt. You
will broadcast the recall wave at exactly one o'clock. If I haven't
succeeded in finding Joan by then, I'll discard my own Belt and stay
on over there in Arret with her.... I'm ready to start now, whenever
you are."

Benjamin Marlowe raised his hand to the switch in the projector's
control panel. "Good-by, Larry,"--the old man's voice shook a trifle
in spite of himself--"and may God be with you!" He closed the
switch.

A great burst of roseate flame leaped toward Powell from the
projector. The laboratory was instantly blotted out in a swirling
chaos of ruddy radiance that swept him up and away like a chip upon
a tidal wave. There was a long moment during which he seemed to
hurtle helplessly through a universe of swirling tinted mists, while
great electric waves tingled with exquisite poignanc