- Script:
- Gardner Fox
- Pencils:
- Mike Sekowsky
- Inks:
- Sid Greene
- Colors:
- ?
- Letters:
- Gaspar Saladino
- Genre:
- Superhero
- Characters:
- Justice League of America [Superman [Clark Kent; Kal-El]; Flash [Barry Allen]; Green Lantern [Hal Jordan]; Green Arrow [Oliver Queen] (all Earth-1)]; Justice Society of America [Hourman [Rex Tyler]; Wonder Woman [Diana Prince Trevor]; Johnny Thunder; Mr. Terrific [Terry Sloane]; Wildcat [Ted Grant]; Hawkman [Carter Hall]; Robin [Dick Grayson](joins- first appearance as adult); Thunderbolt (all Earth-2)]; Black-Sphered Villains [How Chu; Gem Girl [Claire Morton]; Money Master [Horace Rowland]; Smashing Sportsman [Marty Baxter] (all first appearances)] (villains)
- Synopsis:
- The JSA, with new member an adult Robin, confront and are defeated by four normal persons on Earth-2, powered by black matter from another universe. When they ask for help from the JLA using Johnny's T-Bolt, he brings them a battered JLA team, suffering the same problem as their counterparts. Both groups them learn the black matter's origins, and resolve to end the problem on Earth-2 first, lest both worlds be destroyed.
- Reprints:
Story continues in #56. Credits for script, pencils and inks confirmed from Julius Schwartz's editorial records, provided by DC Comics (May 2007).