Apparently, that 90's Superman never died and has been in hiding on a different Earth with Lois and his son Jon. But when the new 52 Superman died of kyrptonite poisoning it was time for him to return to be the protector of the Earth. While being back as Supes he encounters a Clark Kent that claims not to be Superman, just plain old Clark. He appears in numerous issues and never does anything spectacular but you know something is up with him.
In this Superman Reborn event that crosses between Action comics and Superman Rebirth, we learn who this mysterious Clark Kent is, the fate of the New 52 Superman and more about the tie in with the Watchmen. Spoilers ahead.
We open with Ozmandius realizing that one of his prisoners had escaped and doomsday, Red Robin and the other prisoner are laughing at him.
Clark Louis and Jon are celebrating their wedding anniversary in Hamilton when a knock comes to the door. It's the other Clark that for 17 issues said he wasn't superman.
He leaves a photo album at the door and leaves. it says The Kents on it and is filled with pictures of the kents from Louis to Lana and grandparents of Clark.
All of a sudden the house begins to disappear and Jon along with it. As hard as dupes tries nothing works and Jon vanishes along with the house and it's contents.
Supes and Lois go looking for the other Clark Kent and when they find him he reveals himself as Mxyptlk. And he says that he is responsible for shoes getting his secret identity back and wants to know why Supes didn't save him.
He removes Jon from Lois memory and returns them to reality.
We get the story of why mxyptlk was takes by Oz. He has set a path for supes to follow and he doesn't want mxyptlk to fuck it up.
Mxy screams his name backward and it breaks him out of oz's prison where he returns to earth and takes on the Kent persona. Once he remembers that supes didn't come to help him he then kidnaps Jon.
Supes Clark and Jon are in the 5th dimension. Supes agrees to ply mxy game and see if he can find Jon. Meanwhile Jon gets saved by these red orbs that end up being new 52 supes and Lois who have no idea who Jon is because in there reality Supes and Lois don't even date, nevermind have a kid.
So new 52 supes and Lois' reality merges with the rebirth reality because Jon was able to join them in the 5th dimention thus ruining the plan that Oz had in store. We get a tease of Mars at the end so will Dr Manhattan step in now?