Notes:
On sale date from the publication date found at the Catalog of Copyright Entries, Part 2, Periodicals, New Series, Volume 35, January-December 1940, Numbers 1-4. Class B periodical. Copyright number B 439740.
Character(s):
K the Unknown [Doug Danville] (first appearance; only appearance); Terry Dane (first appearance); Sigmund Rathko (first appearance; villain)