Earth 23 is a parallel earth and almost a complete opposite of ours. On the parallel earth a group of villains known as the Injustice Syndicate were able to defeat their enemies and take over their world. However, a hero known as the Red Hood was able to send a distress call to the parallel earth with his phase oscillator before he was discovered by the Injustice Syndicate who used it to prepare their invasion of Earth 2.
Owlman travelled to Earth 2 to scout the area but ended up being captured by Batman who disguised himself as Owlman and travelled to Earth 3. When he lied saying that everyone on Earth 2 had powers he was dismayed to find out that the backup plan was to destroy the other earth. Secretly teeming up with Red Hood to stop the syndicate, they freed the other heroes and after a long battle the Injustice Syndicate fell. Only the leader, Silver Cyclone remained. He revealed that his bomb only destroyed organic matter and that when it went off both the heroes and villains would be dead and he would be left to enjoy a world without humans. Just as he was about to blow up the Earth with his bomb Red Hood threw a spade into the side of Cyclone's head destroying him. Batman thanked the Red Hood for his help and travelled back to his own Earth telling him to expect an owl shaped package momentarily.