The powers that be have isolated the universities, where college dissidents have been literally forced underground by the government as a result of the Second Civil War between Nixon's presidency and all forms of civil disobedience. America is now a police state with a Police Marshal at the top and five regional Police Generals below that position. A person can't function for long in society without a host of official IDs, and as the students and protesters don't have such ID's, they're easily discovered by the seemingly endless series of official checkpoints throughout America.
But the masses -- especially those living away from the depressed inner cities -- still need entertainment. And Jason Taverner, popular talk-show host and singer, is one of America's most popular and well-paid entertainers.
However, one morning, Jason Taverner wakes up in a fleabag hotel room with no ID. He at least has 5000 dollars in his pocket. But as he soon discovers, he no longer exists either on record or in anyone's memories. What has happened? Well, it's a Philip K. Dick novel, so the answer turns out to be typically reality-bending.
Taverner's odyssey to find out what has happened takes him through various levels of the new American society, from ID forgers to police bureaucrats to middle-class potters. The novel soon provides him with a co-protagonist, Police General Felix Buckman. Buckman isn't actually a bad guy -- he's spent his career at the top trying to save the lives of the enemies of the State, though he's still a dystopian bureaucrat with more than one skeleton in his closet.
This is one of Dick's sharpest, most focused later novels. Nonetheless, it still abounds and swirls with those brilliant, disturbing flashes of Dickian imagination. Most prominently in terms of the novel's critique of certain beliefs both real-world and science-fictional, in this world, there are highly intelligent people genetically engineered to be supermen (indeed, Taverner is one). They're called 'Sixes,' after their batch number (a nod to Dick's own Nexus-6 androids in Do Androids Dream of Electric Sheep?, the basis for Blade Runner?). But the sixes couldn't conquer the world because they can't stand being around one another: the superman abhors the superman, and thus fails to conquer.
There is a bizarre form of phone sex that can cause permanent brain damage and ultimately death. There are flying cars and pin-sized nukes and... conventional 33 1/3 LPs and 45s in juke boxes? Cigarettes are heavily regulated by the State, while pot and mescaline are readily and legally available to all. African-Americans are now seen as a rare, exotic group that's close to extinction thanks to decades of genocidal eugenics. And behind it all, there's a dystopia based on fear and paperwork.
There's also hope, though, especially as the novel ends. The dystopian police state will not endure as long as people are capable of small acts of empathy and compassion, and of creating beauty. And entropy affects everything, good and evil, the same: the dystopia will succumb to entropy just like everything else. It's a fine novel that sends back echoes of the world we live in, refracted by Dick's prismatic and unique imagination. The title is derived from a song (an ayre, actually) by 16th-century composer John Dowland ("Flow, my tears, fall from your springs"). You'll have to read the novel to discover the significance. Highly recommended.