Back in the 60s, you could witch-hunt Communists to gather and exercise political power; it worked great. HUAC's known for it, but J Edgar Hoover's FBI did it, too. Accusing an enemy of Communism put them on the defensive and built your case that investigating Communists was a worthwhile thing to do: after all, you keep finding Communists... except that the accusations don't stick, but as long as you accuse plenty of other people in-between time, it'll still look like you're doing something important.
Ronald Reagan, back when he was an actor, had a cozy relationship with the FBI. He informed on some people he suspected of being Communists. (Later on, he denied doing this. The book's author and some lawyers had to jump through many FOIA hoops to get FBI records revealing how many folks Reagan fingered.)
The FBI, rather than investigating crimes and keeping the peace, ended up fanning the flames of protest. UC Berkeley's Free Speech Movement started out as a protest on the school's ban on political speech on campus: if you set up a card table with pamphlets about some political cause, you got kicked out. This turned into a protest which died down when the school's head conceded the ban was a bad idea—something the substitute-head had done while the real head was out of town. But Hoover's FBI was eager to paint Berkeley's students as Communist dupes; a reporter who they often used for leaks soon published an article about Commie students defying the school administration; this led the UC regents to lean on the school administration to stand firm. And so the FSM didn't fizzle out, but turned into protests, organized protests, and eventually over-reactive rioting and over-reactive police shootings and… And you kind of want to put the book down so you can take a breather and calm down a bit.
The FBI played fast and loose with the facts. They went behind the scenes to get suspected radicals fired: they'd send an employer a message saying that so-and-so had been accused of being a Communist—but not mention that they'd investigated the accusation and found it untrue. If you're thinking "It's not the FBI's job to get radicals fired," you're right, this was part of the FBI's COINTELPRO New Left program, illegal persecution of folks who, in hindsight, turned out not to have deserved such. This was the program who tried to shut down the Civil Rights Movement, to blackmail Martin Luther King.
My parents were in Berkeley around this time; I now understand some of their views. They don't think much of Ed Meese. Before he became attorney general under Reagan, he was a deputy District Attorney who prosecuted student protestors; when he got involved in planning police response, things were pretty much guaranteed to get out of hand. If police got out of hand, reports of violence could then be used to declare the situation out of control, and in need of more control. Reagan ran for governor on a platform of clamping down on Berkeley's subversives. But he chose to blame students rather than the FBI and a DA.
It's well written, but it's a difficult read. Good people suffer, innocents get stomped by Hell's Angels, shot by riot police, accused of treason. A politician uses these innocents as scapegoats, and eventually becomes president. Now it's 2013; Bradley Manning uncovered evidence of a murder and exposed it; the USA government prosecutes him. If it weren't for our history, we might think our government was justified somehow. But now what can we think but that it's another attempt to shut down someone who dared point out where we have gone astray?