This is a 'Reawakened' setting, that is to say, one where the 'Reawakened' advantage is important enough that most or all of the PCs should probably have it.
In this instance, people have very recently as of campaign start (meaning some time in 2020 if you don't want to fudge the dates) begun remembering past lives as masked 'mystery men' and 'mystery women' (heroic and otherwise) in the 1930s and '40s - and earlier, in a few cases. With those memories have come the skills and abilites that they once possessed, including some who were quite powerful. Some of these people remember dying (and in certain cases, coming back and adventuring as ghosts or undead), but a few do not, either due to the circumstances of their deaths, or because they were alive in mid-to-late 1950. No-one whose memories go past about mid-June of 1950 remembers dying, and no-one has any Reawakened memories that go later than about early November, 1950. During that period, a number of seers and other precogs reported that something was coming, that something big was going to happen, but they didn't know what. There are very few physical records of these people from that era, though, outside of comic books and other fiction... and sometimes not even then. In a number of cases, the cities and other regions that they remember do not exist, or are very different, and the records of people they knew are often likewise missing, or have strange alterations, like dates of death that are earlier or later than they should have been (e. g. the politician that you saved from an assassin died then, because you weren't there). It's as if some great and terrible power erased them all from existance.
What really happened:
Spoiler:
What they don't know in-setting, and might never know, is that a reality quake connected a pretty mundane close parallel of Homeline (Paul Van Zandt did not invent anything that would make him famous) with a world experiencing the Golden Age of Superheroes (something like the
Wold Newton Universe with more superheroes, and with any serious contradictions smoothed over or completely redacted). The other worldline now has memories of what they mostly consider a 'dark future,' but they also have a greater understanding of easily-reproducible science and technology (as opposed to Superscience), as well as copies of some items owned by the person whose memories they recieved (if the modern character has modern Signature Gear or Signature Assets, Weapon Bond, Equipment Bond, or similar, the Golden Age character definitely got a copy, and they might also get copies of non-Signature items that the modern character just owns and cares about). They may or may not be looking for a way to find the other Earth that they contacted - though of course, not all of them believe that it
was another Earth.
Because these powers are so new, they have yet to have much effect on law, politics, or culture, and may even be believed to be hoaxes or urban legends at the time the campaign starts - not even that, if you start the first session with the first people who woke up with powers and new memories. Your actions may well shape how the world, or at least your part of it, responds to people with strange powers running around.
(I may be going too far in trying to avoid the character limits, but that is, I hope, better than doing too little and then needing to divide posts in illogical places. Also, I'm sure that I've seen spoiler tags working on this forum, so the above apparently not working is weird.
EDIT: Apparently you can't label the spoiler box inside the spoiler tag on this forum, like you can on some others.)