On-sale date from copyright registration. An on-sale date of July 20 was listed in a promotional house advertisement that appeared in Superman (DC, 1939 series) #6 (September-October 1940).
This issue has variants:
Batman [Bruce Wayne]; Cat-Woman [Selina Kyle] (villain); Commissioner James Gordon; Robin [Dick Grayson]; E. S. Arthur (wealthy gem collector, death); Johnny (newsboy); The Crime Syndicate, Inc. [The Joker; Weasel; Mugface; Circus Charlie (poses as Batman, death); others unnamed] (villains, introduction for all except The Joker)
Synopsis
Learning the Joker is hospitalized with wounds, the members of the Crime Syndicate make plans to rescue him to lead their mob again. But the Joker has planned a double-cross and the appearance of the Cat-Woman complicates matters.
Batman [Bruce Wayne]; Robin [Dick Grayson]; Cyrus Craig (museum owner); Adam Lamb [aka Wolf] (villain, Craig's museum custodian, introduction, death); Wolf's gang (villains, introduction for all)
Synopsis
By an unfortunate accident, Adam Lamb becomes a psychological Jekyll and Hyde at midnight each evening, only to revert to his mild-mannered self during the day.
Batman [Bruce Wayne]; Commissioner James Gordon; Robin [Dick Grayson]; Harley Storme (millionaire, death); Portia (Harley Storme's niece); Abel Storme (Harley's brother, death); Carl Storme (Harley's brother); Roger Storme (Harley's son, death); Clubfoot (introduction); Ward [as Clubfoot] (villain, the Storme family lawyer); Varrick (villain, gambler, introduction); Tommy (villain, Varrick's partner)
Synopsis
The contents of a strange will leave each of the heirs with strange tokens with inscriptions on them, not realizing that, if they are all united, the tokens will reveal the location of a gold mine.
Batman [Bruce Wayne]; Robin [Dick Grayson]; Professor Drake (death); Goliath (prehistoric man, death); pygmies (villains, some die); Hackett (villain, circus owner, introduction); Snead (villain, circus owner, introduction); Grimes (villain, introduction, death)
Synopsis
Professor Drake brings back from Africa a "missing link" whom he intends to civilize, for the benefit of all civilization. But he learns, as do the Caped Crusaders, that sometimes men act more like beasts than someone like Goliath!