Another imaginative and action-packed series of stories by writer Gardner Fox and artist Mike Sekowsky. This run of stories, first published from 1965-1966, introduced a number of classic villains: The card-themed Royal Flush Gang, the brutish Shaggy Man, and the bizarre energy-being The Unimaginable. The old-time heroes of the Justice Society and Metamorpho the Element Man put in guest-appearances. The heroes are challenged both physically and mentally, as each story resolves around a mystery or puzzle that has to be solved before they can defeat the bad guys. It's a formula of sorts, but Fox never runs out of crazy, colorful variations on his theme.
There are two noteworthy changes in this volume. The artwork gets a visible upgrade, as Mike Sekowsky's pencil art is now being finished by a number of different inkers: Frank Giacoia, Sid Greene, and Joe Giella. No offense to the previous inker, Bernard Sachs, but these fellows give the artwork much more detail and drama than it had before.
The other change is that the Batman television show debuted. You can tell, because Batman is suddenly much more prominently featured in the stories and covers. DC Comics wasn't shy about capitalizing on his sudden popularity.
For fans of the superhero team genre, this is the foundational text. Fox and Sekowsky created the mold that everyone else followed. But more than anything else, it's terrifically well-crafted entertainment.