To the teeming city of the Golden Gate the sinister Doctor Yen Sin had transferred his base of operations-and there, under cover of the fog-shrouded Frisco night, he set loose the most ghastly weapon in his whole armory of mysterious torture devices-the curse of the Singing Mummies. In ten minutes by the clock, to the accompaniment of that insidious, eerie music, living men and women underwent their ghastly metamorphosis, became fit occupants for the coffin-cases of ancient Egypt. How could the saffron-skinned crime-emperor accomplish the change? How could even Michael Traile, the Man Who Never Slept, hope to cope with the devilish Thing?