According to archive.org, the copyright to Masters of Deceit ran out in 1986 without being renewed so it is now in the public domain. I downloaded a scanned version from the site. It's been openly available there for some time, so I figure they're probably right about the copyright. I skimmed through the book pretty quickly and I was mildly surprised by several things.
It's very well written, in a plain and straightforward style; it's not dry but it's not a rant. At least on many important points Hoover appears to be quite sane and decent. He acknowledges that industrial capitalism in Marx's day was indeed rife with many abuses. He distinguishes between the millions of unfortunate citizens of the communist bloc in his own day, and the few communist rulers who controlled their lives.
Hoover's surveys of the lives and works of Marx, Engels, Lenin and Stalin seem to be accurate and clear, as far as I can tell by comparison with some more recent scholarly works by academics who seem pretty neutral because they treat communism as past history. The only really odd thing is how Hoover literally passes over World War II in a single sentence, referring to it merely as an upheaval. The importance of the Great Patriotic War for the Soviet Union and its system obviously deserves far more mention than that. It seems that Hoover just didn't want to say anything remotely positive about communism, and it would be impossible to discuss the Eastern Front of WW2 without acknowledging that communism succeeded in maintaining an enormous and successful war effort, very much comparable to the triumph of industrial democracy. The current consensus seems to be that communism isn't as good as industrial capitalism even for waging total war, but that it is at least fairly effective at that one extreme task of economics. When he should have given even the devil his due, Hoover ducked.
The biggest surprise for me was the portrayal of the American communist party as a cult that made outrageous demands on its members, demands of the kind that are all too familiar to Scientology watchers. I've never read any other side of the story from the one Hoover tells, but for what it's worth I find his picture convincing. Militant communists are nothing if not dogmatic, and that kind of extreme dogmatism does seem to go along with extreme control of people's lives.
The other big surprise I found in Masters of Deceit was one of those surprises where you're surprised to see exactly what you were expecting, because even though you were expecting it you couldn't quite believe it could really be like that. Hoover was really concerned that communists were threatening to take over the United States. Looking back today, this seems about as ridiculous as the idea of Scientology clearing the planet. So it's strange to read page after page taking the notion very seriously. The American communists may well have been comparably many and well organized to Lenin's Bolsheviks, but the USA in 1958 was just nothing remotely like Russia in 1917, an absurd medieval holdover that was losing a huge war. In a failed state like late tsarist Russia, even the Sea Org could take over, with some luck. That doesn't mean the Sea Org is any threat to America today. So Hoover convinced me that communists needed to be saved from the communist cult, but not that his country needed to be saved from communism.
I'm prepared to cut J.E. Hoover some slack and allow that, in 1958, things may have looked very different. Hindsight is 20/20. Half his book may look silly today, but that doesn't mean it was a silly book when he wrote it.
It's a terrible shame that he didn't retire long before that, though, and write the same book as a private citizen.
Instead, J. Edgar Hoover was director of the FBI for some 37 years, dying in office at age 77. That's a statistic worthy of the Soviet gerontocracy, a gruesome shame on a supposedly free democracy, and a grim irony for the United States of America out of all democracies, when the American constitution is so aware of the fact that power corrupts. There is and can be no excuse for letting one man hold that kind of office for that long, and the fact that it happened overshadows everything else that J. Edgar Hoover could possibly have done. Even if his entire 37 year term had been nothing but the purest ideal of public service, just by hanging on to such an office for so long, Hoover damaged his country badly.
How much of current American authoritarianism, all the spying on citizens at home and torture on foreign soil, can be traced back to the cultural seeds planted by J. Edgar Hoover, in setting the precedent that security services should be a people apart from the people, and a state within the state?