John Lennon survives his assassination attempt to end up the defacto leader of the American opposition at the dawn of Reagan's America.
A braintrust of left-leaning scientists and artists (actual historical figures) tries to turn the tide back in the early eighties via precipitating a wide-scale telepathic awakening but things backfire very very badly, some in realistic ways, some in science-fictiony ways, until much of the United States is disbanded or ruined, except for the Eastern Seaboard and middle South which are being psychically manipulated into some kind of shadow play version of 1950s America.
The poorly organized underground, barely held together by the force of Lennon's fame, takes one last ridiculously-unlikely shot at success... building a machine to send out a distress call to parallel timelines, in hopes of reinforcements... but all it ends up doing is plucking a sort of timetraveller out of the stream of reality and depositing him, suddenly powerless, at their feet.
And the time traveller (more a rider of parallel dimensions, really, there's no going backwards, there's no changing the past, there ain't no going back) isn't particularly heroic, he isn't trying to set right what once went wrong or anything, he's been mostly squandering his abilities trying to find a world where a group of friends from his youth are all alive and in tact so that he can retreat back into the best part of his life.
A journey out of Manhattan, through the stitched-together ruins of the upper Midwest, to try and petition the only known person with time-type powers on that world ensues... John and his close circle of friends hoping that perhaps he'll help them upon meeting one of his own, the timetraveller hoping he can get help getting his powers back so he can return to his sad stunted quest.
Everyone's exhausted, everyone's tired of running but nobody really knows how to give up, just on momentum.
Bob Dylan is a born-again Christian country music star in the shadow America, Country Rob Zimmerman.
Kurt Vonnegut and Philip K Dick are two of John's closest surviving advisors.
The nexus of the telepathic control network are forty-or-so comatose telepaths, wired up to machines, broadcasting out complacency from the tops of the tallest buildings remaining in New York, the Twin Towers of the World Trade Centre.
At this point, I have no idea if it is proof that I am entirely mad.