When movies like "Guilty By Suspicion" come along I find myself asking why.

After all, the McCarthy era, the House Un-American Activities Committee, the Hollywood Blacklist - this shameful period of the communist witch hunt in the 1950s - has been explored by other films. And, to be honest, there's nothing particularly illuminating or fresh about this subject that "Guilty By Suspicion" brings to light.The answer to the question is probably twofold. First, it's a subject that people who went through the blacklist feel passionate about and, no doubt, need to express their feelings. (Many participants in this film had such experiences.)

Secondly, it's an opportunity to introduce the subject to a generation of moviegoers who may know little or nothing about it. The truth is, of course, that most people who go to this movie will probably be older and already aware of the subject matter.

On its own terms, however, "Guilty By Suspicion" is an intelligent, sincere film that manages to make clear why so many people at the time were unwilling to cooperate with this government-sanctioned terrorist action. And there is a subtle subplot that gives the film an extra level.

Robert De Niro stars as a film director who once went to a couple of communist party meetings years earlier and was thrown out because he argued too much. But his presence at those meetings is enough to drag him before a Senate subcommittee that is accusing anyone associated with the Communist Party of being a traitor.

De Niro doesn't want to testify - not because he has anything to hide but because he knows he will have to name names, say that his friends are communists or that they attended meetings or who knows what.

In other words, he is willing to tes-tify about himself but he doesn't want to implicate his friends - especially his friends who are innocent.

Modern audiences may ask, "Why should he?" Indeed, that is the question. But an understanding of the nationwide paranoia that gripped the United States in the '50s, in conjunction with the proliferation of nuclear weaponry, helps in the understanding - if not the justification - of the situation.

For me, someone who was a child in the '50s and saw much of this firsthand, if only on television and in newspapers, that's not really necessary. But for young modern audiences it may be.

There is a lot of excellent period detail and uniformly fine performances by a very good ensemble cast but never a real sense of why this is happening in the first place.

At any rate, the story has De Niro initially refusing to testify and finding himself blacklisted. It's not an overt thing - no one says, "We won't hire you because of government pressure." It's more that he simply can't get hired; everyone has an excuse but the fact remains he's out of work for a long period.

Meanwhile, his unemployment allows De Niro more time to devote to his young son and ex-wife (Annette Bening, from "The Grifters"), whom he has virtually ignored in the past because he's such a workaholic.

This subplot, in its own quiet way, becomes the film's most powerful link. De Niro begins to gradually discover just how important and meaningful family ties are as opposed to the fame and fortune of making movies, which is more fleeting.

It's not an overt message and certainly not an original one, yet the way it sneaks up on the audience quietly and powerfully results in its having even more impact than the more obvious point that the McCarthy hearings marked a horrible, shameful period in our history.

De Niro is brilliant in a role that is filled with nuance and gentle undertones. He is tormented as much by the fact that he can't work as by the FBI's harassment tactics. Despite his powerful, flamboyant award-winning turns in "Raging Bull" and "Awakenings," it is the real test of an actor's ability when he plays a more "normal" human being whose emotions are more subtly played - and De Niro is in peak form here.

He is ably assisted by George Wendt (TV's "Cheers"), as his best friend, a screenwriter headed for a fall; Patricia Wettig (TV's "thirty-something") as an alcoholic star who becomes a tragic victim of the blacklist; Sam Wanamaker as a Hollywood lawyer who is playing the game; director Martin Scorsese as a moviemaker who leaves Hollywood rather than become a victim; and the aforementioned Bening, who, as a sweet, sincere and supportive woman still in love with her ex-husband, effectively plays the complete opposite of her "Grifters" character.

The film marks the first-time directing effort by veteran producer Irwin Winkler (who also scripted) and it's a good job though a bit too slow-moving in places. Still, it builds nicely, if not unexpectedly, to the rousing climax (which resembles the final moments of "The Front," a 1976 dark satire on the same subject starring Woody Allen).

"Guilty By Suspicion" is rated PG-13, which is notable for the surprising amount of R-rated profanity it contains.