"Meet the Master of Reality... Dominus!"
The four Supermen on the cover are Supermen from different time periods.
Meet the one villain that no Superman from any time period - Golden Age, Silver Age, Modern Age, and beyond - maybe able to defeat.
Story continues in: Adventures of Superman #561
"1998 33"--Triangle in upper right hand corner.
The Superman's descendant in 2999 together with other heroes like Aquaman 2999, Batman 2999, Big Barda 2999, Flash 2999, Green Arrow 2999, Green Lantern 2999, Hawkman 2999, Martian Manhunter 2999, Robin 2999, Supergirl 2999, and Wonder Woman 2999 officially announce the formation of a superhero team called the Justice Alliance when a white-haired girl, appears to Superman to warn him about the reality he is in and the danger that he will face. Suddenly a camera flash causes him to see in a moment all four realities he was cast in: the 1960s, the 1970s, the 1940s that ended up becoming the present day, and the 2999 reality. In all four realities, the little girl became the female cosmic entity called Kismet who said that these realities were created in order to destroy Superman. However, the creator of these realities, Dominus, says these were created to find and destroy Kismet, and soon all four realities vanish as the Supermen of these realities merge together back into the single present-day Superman. As Superman and Kismet vanish to another part of the universe to talk about the problem they will confront, when suddenly Dominus appears to attack Kismet to the point of weakening her into a ball of energy and Superman unable to save her.
There are versions of characters in the future that appear in this comic book, those are:
Big Barda (2999)
Green Arrow (2999)
Green Lantern (2999)
Lena Luthor (2999)
Martian Manhunter (2999)
Wonder Woman (2999)