Don’t stand on one foot waiting for the film version of this devastating history of the political left in Hollywood. The film colony obviously prefers romance and myth to the facts, and nothing gets a salute faster around a Bel Air swimming pool than a sanctimonious reference to the blacklist.

So let’s begin by stipulating, as Ronald and Allis Radosh clearly do, that the blacklist was wrong. Artists, even empty-headed actors, should not be denied a livelihood because of their political beliefs. The studio chiefs who invented and ran this unemployment scheme have plenty to answer for, as do the grandstanding politicians who coerced them to do it. All this has been explored at length, if not in perfect clarity, in such mainstream movies as “The Way We Were,” “Guilty by Suspicion,” “The Front,” and “The Majestic.”

What gets very little attention in Hollywood, on screen or off, is the story of how Soviet agents and the Communist Party USA actually did infiltrate and influence the film industry. Hollywood has paid even less attention to the background of the story, including Stalin’s deal with Hitler and the increasingly bloody Soviet purges. It’s no accident, as the comrades would say, that Hollywood’s Reds stuck with “Uncle Joe” every zig and zag of the way. Roosevelt was a warmonger for a year or two, then a hero. Civil Rights was a front-burner issue before Pearl Harbor; after war was declared, Civil Rights was “divisive.” And, yes, Finland was to blame for the Soviet invasion of Finland.

The Radoshes have done an estimable job filling in the blanks with the names of communist agents and officials and the specifics of their meddling. The result is going to make Barbra Streisand crazy. But the best thing of all (well, apart from making Barbra crazy) is that the Radoshes are both nuanced and fair. They know how to separate the simpletons, like matinee idol John Garfield, from the truly loathsome, like playwright Lillian Hellman. And they are no kinder to the House Committee on Un-American Activities (HUAC), with its yahoo anti-Semite chairman, than to the communists and Fellow Travelers.

Hellman is so bad she’s scary and funny at the same time. One of the better anecdotes in the book has her arriving at a fancy Bel Air mansion “fashionably dressed all in white” on the day of the Nazi invasion of Russia. “The Motherland has been attacked!” she intoned. Nobody knew whether she was joking or serious. Another has her in an exchange with writer Budd Schulberg, by this time a former communist who had named names:

His decision to testify made Schulberg a marked man with his old friends. In the 1960s his old acquaintance Lillian Hellman approached him at a party and proceeded to reprimand him for testifying as a friendly witness before HUAC. ‘I really felt guilty about all those years I was in the party,’ he responded, ‘when such terrible things were happening to writers like Isaac Babel.’ To his astonishment, Hellman asked, ‘What happened to Babel?” He looked at her in disbelief: ‘What happened to Babel? He was murdered [by Stalin] in 1940.’ Hellman’s ignorant and dismissive reply staggered him: ‘That’s anti-Soviet propaganda.'”

Actress Jane Fonda would later play Hellman in a hagiographic film, “Julia,” that got just about everything wrong – about Hellman, about her lover, Dashiell Hammett, about the period, about the nature of their political commitments. Bogus from beginning to end, it was a middling hit in 1977. But the worm began to turn in 1984, when writer Mary McCarthy, appearing on “The Dick Cavett Show,” famously stated that everything Hellman said was a lie. This was followed by a libel suit, which was still in process when Hellman died.

Mr. Schulberg, the author of “What Makes Sammy Run?” and screenwriter for “On the Waterfront,” turns out to be one of the more likeable and witty characters in this book. He is also one of the few who seemed to understand what the Bolshevik Revolution meant for real people who were not part of the Hollywood scene. “My guilt is what we did to the Czechs, not to Ring Lardner [a blacklisted writer],” he once noted. In later years, when the extent of Stalin’s crimes became known, he said he always liked to think of himself as being among “the pre-mature anti-Stalinists.”

If Mr. Schulberg wore the burden of naming names lightly, the late film and stage director Elia Kazan suffered lifelong torments for cooperating. He actually had made a complete intellectual break with the party and was a committed anti-communist by the time he was subpoenaed. But he hated the HUAC almost as much as he hated the communists, and he felt enormous guilt for naming friends like playwright Clifford Odets.

In the end, Odets named Kazan in his own appearance before the HUAC. Why then, was Kazan singled out for the most vituperation from the left? The Radoshes believe it is precisely because he was so eloquent in his condemnation of communism as a threat to American lives and liberty. The others merely squealed, but he declared that communists were wrong, dangerous, and part of a conspiracy.

The left has a long memory. In 1999 the Academy of Motion Picture Arts and Sciences voted to give Elia Kazan a Lifetime Achievement Award for directing works like “On the Waterfront,” “A Streetcar Named Desire,” and “Viva Zapata.” Kazan was in his 80s and in poor health, but his critics raised a chorus of protests. When the old man approached the podium to accept his award, “a group of Hollywood’s finest – including Nick Nolte, Ed Harris, David Geffen, Sherry Lansing, and Richard Dreyfuss – sat stonily while others gave a standing ovation.” Their rejection, not his achievements, became the story of the night.

This book is a major contribution to the understanding of a painful period. With any luck, it is only a first volley.

Mr. Willcox last wrote in these pages on the lives of John F. Kennedy, Lyndon Johnson, and Richard Nixon in 1948.