DC Comics released Crisis on Multiple Earths to introduce (or refresh) the reader to the concept of multiple earths coexisting in the same physical space, and as a background to the multi-part epic Crisis on Infinite Earths. This volume collects four different stories (each encompassing two issues) involving the Earth-One Justice League of America (the most familiar DC stars such as Superman, Batman, and Wonder Woman) and the Earth-Two Justice Society of America (older heroes, some with Earth-One counterparts such as the Flash and Green Lantern, but some unique heroes such as Doctor Fate and Hourman), all from the mid-60s and written by Gardner Fox with drawings by Mike Sekowsky.
The best story introduces Earth-Three, where only criminals have the super powers. Bored with committing easy crimes, the Crime Syndicate of America--a band of supervillains with knockoff costumes and dumb names ("Power Ring" and "Johnny Quick")--challenge the JLA and JSA to battle. The other stories involve the Crime Champions of Earth-One and Two, Johnny Thunder's Thunderbolt, Solomon Grundy and Blockbuster. For more crossover action, Crisis on Multiple Earths was followed by a volume 2. Alex Ross did the cover paintings for all three Crisis... books. --David Horiuchi, Amazon.com