The protagonist, David MacKinnon, is a romantic idealist up for trial for assault. Since the government fears that he will repeat his action, he is given a choice: either allow trained psychologists to fix him, or leave to an area known as Coventry. MacKinnon chooses to emigrate so he can escape the boredom of a too civilized society. He is sent to the rugged outland beyond the Barrier, where people who refuse to abide by social norms are exiled, rather than submit to radical psychotherapy. He finds out that the peaceful anarchy he envisioned is a bleak dystopia split into three independent countries:
New America, a corrupt democracy with a dysfunctional judicial system, lies closest to the entry point to Coventry and is the most populous
the Free State, ironically named, is an absolute dictatorship ruled by the "Liberator", with an even harsher penal system, and is frequently at war with New America, though not when the story takes place
the Angels, remnants of the theocracy from "If This Goes On—", in the hills north of New America, living under a new "Prophet Incarnate"; it is implied they are the fewest in number of the three
He is immediately jailed in New America, losing all his goods. Befriended by a man he knows only as "Fader" Magee, he breaks out of jail. He then finds out that New America and the Free State are combining for an attack on civilization. He and Fader break out of Coventry separately to warn the community from which he's just emigrated. He then learns that the Fader is actually an agent of the United States Army, and that he has redeemed himself by risking his life to warn the rest of the country.