K-4 In Disguise

Printed in Daring Mystery Comics #2 (Feb. 1940) with 10 color pages. Reprinted in Marvel Masterworks: Golden Age Daring Mystery - Volume 1 (Jan. 2008).
"Captain K-4 is assigned to infiltrate and help to destroy the ammunition depot located at the Nazi seaport of Kurtzberg, while disguised as a Gestapo agent."