The refugees from the DC multiverse try to convince Power Girl and Batman to join them into restoring Earth-2. The problem is it doesn't appear that everyone agrees on how to do that. Meanwhile Earth-1s villains are working together to bring down the world and bring it under their control.
The only one not included is the Joker and he is not going to let it go. Joker is not the only Gothamite who is having problems. Batman's creation Brother Eye has taken control of the O.M.A.C.s and is using them to punish heroes that have gone to far. Lastly, Wonder Woman is fighting the O.M.A.C.s at Paradise Island and it don't look like her of her fellow Amazons will survive.