The issue begins with a multi-page summary of a number of events that happened throughout the comics. Mainly just the Viltrumite stuff. I'm not sure why since it's not like there's going to be many new readers on the last issue.
Mark goes off into space to play emperor to his people and leaves his bastard kid Marky on earth. Then we get a timeskip and teenage Marky gets an Invincible costume and goes off to fight crime.
Mark's daughter Terra also grows up and is shown flying around space in her own Invincible costume.
The brain of Robot is lonely. (that's all we get)
Some kid with a pet fox from another dimension pops up and blames Mark for killing his father or whatever. Unless I missed something, it isn't shown what the resolution here is.
Older Mark has been leading his people towards ending wars and making the universe a more peaceful place. For some reason one-eyed Allen doesn't like this and thinks it's bad because planets want to leave the coalition. We see them fighting each other and Allen remarking that Mark was right in like one page.
Atom Eve is shown on her deathbed (from old age), dies, and then immediately comes back young again. Remarks that she must be immortal. OK.
We see the result of a fight between Mark and Marky back on earth. Looks like Marky became kind of an asshole and hated his dad for "abandoning" him even though he has an adopted father. Now he's reformed.
Mark turns the Viltrumites into a force for good and it appears that the final page ends a good 500 years later.
