An explosion in the middle of town was caused by atomic experiments, and Clark Kent gets the story. He soon finds the Ultra-Humanite is also interested in the technology, but by the time he arrives on the scene, the inventor has been captured, and his technology has been rigged to destroy Metropolis unless Superman steals a valuable set of jewels for Ultra.
| Barcode | N/A |
|---|---|
| Character | Superman (Kal-El / Clark Kent), Ultra-Humanite (Dolores Winters) |
| Cover Date | February 1940 |
| Issue | 21 |
| Rating | N/A |
| Artist | Homer Fleming, Bert Christman, Bernard Baily, Fred Guardineer, Sheldon Moldoff |
| Colorist | N/A |
| Cover Artist | N/A |
| Cover Colorist | N/A |
| Cover Inker | Paul Cassidy |
| Cover Painter | N/A |
| Cover Penciller | Joe Shuster |
| Cover Separator | N/A |
| Editor | Whitney Ellsworth |
| Editor in Chief | Whitney Ellsworth |
| Inker | N/A |
| Layouts | N/A |
| Letterer | Bernard Baily |
| Painter | N/A |
| Penciller | Joe Shuster |
| Plotter | N/A |
| Scripter | N/A |
| Separator | N/A |
| Translator | N/A |
| Writer | Gardner Fox, Ken Fitch, Jerry Siegel |
