"In Each Man There is a Demon!"
It seems that the Justice League is not yet done with the villain Aquarius. Remnants of his power have created evil doppelgangers of several Justice League members. As if things weren't bad enough, Green Arrow seems to be having identity problems. (This story is narrated by Green Arrow and Black Canary)
Black Canary is now on Earth 1 and officially joins the JLA. This is also the first issue with her Canary Cry and Green Arrow is seen for the first time in the JLA with his new costume and attitude.
This issue also includes "The Wonderful World of Comics, a Golden Age I.Q. Test (20 questions with answers) and "The Stars and their Legends" (a one-pager on the legend of Andromeda and Perseus).