New Adventure Comics #8 (20)

In "The Train Robbery, Part 19," the Junior Federal Men Club expands its reach, introducing a secret hand signal for members to recognize one another—while a detailed sidebar explains the science of fingerprints, from their unique patterns to how they’re properly recorded. Cover by Creig Flessel, this 1937 issue of New Adventure Comics #8 (20) blends espionage intrigue with real-world detective techniques, all in a story written in character as Steve Carson.