He struck it a sharp rap, then recoiled in surprise at the effect of his blow, for the entire egg instantly shattered with a tinkling crash like the bursting of a huge glass bubble. So complete was the disintegration of the egg and the skeleton 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 poignancy through every atom of his body.