How long has it been since you left a movie saying, "Now that was a damn good story!"? James Caan's "Hide in Plain Sight" reawakens that kind of old-fashioned enthusiasm, while inducing you to fight back tears of sentimental joy before the house lights go up.

Its a disarmingly effective throwback to human interest melodrama, to the neglect genre of semi-documentary crime thriller best exemplified by Elia Kazan's "Boomerang" and "On the Waterfront" and Henry Hathaway's "Call Northside 777" and "Kiss of Death."

In that tradition, "Hide in Plain Sight" derives from a real-life case history. While fictionalizing that case effectively, Caan and screenwriter Spencer Eastman never lose sight of its uniquely stirring dramatic elements or its social context. Among other virtues, this is one of the few American movies of recent years that reveals a tough-minded understanding of the way the world works and a decent regard for the contradictory nature of human beings.

"Hide in Plain Sight" depicts the ordeal of a devoted father who is separated from his two little kids as an unforeseen consequence of a government program intended to protecct the identity of informats. The story begins in 1967 in Buffalo where the protagonist, Tom Hacklin, was born and raised and has followed his late father into working-class employment, respectability and then disillusionment.

Tom is an eight-year veteran of a tire-plant assembly line. He served in the Marines and had aspiration to a professional baseball career that were terminated by a knee injury. His marriage has flopped and his ex-wife Ruthie has picked up with disreputable boyfriend, a small-time gangster named Jack Scolese.

Jack is arrested for a stick-up and is persuaded to testify against his superiors in exchange for immunity and protection. In fact, he becomes the pilot project of an experimental Justice Department program to encourage mob informers by relocating witnesses in other parts of the country with new identities.

One night Scolese, Ruthie and the kids suddenly disappear from Buffalo, spirited away to a fresh start in Ann Arbor. An innocent victim of this potentially valuable scheme, Tom spends an engrossing, suspensefully distilled year and a half attempting to locate them.

Although a real injustice has been done to Tom, the remarkable thing about "Hide in Plain Sight" is that it exploits this fact for realistic human interest and pathos rather than self-righteous vigilante fantasy or knee-jerk moral indination. Caan and Eastman refuse to let Tom follow in the footsepts of Dirty Harry, Billy Jack or Buford Pusser.

Their hero takes initiatives and even does a certain amound of law-breaking, but his measures remain believaable. They don't transcend his physical capabilities or social opportunities.

For example, when his lawyer loses a preliminary appeal, Tom feels irked enough at the government attorney to take out a little spite. The opportunity arises when Tom, further frustrated by a layoff at the plant and a bad day at the unemployment office, happens to see this attorney park his sports car in the same lot. When Tom gets into his venerable sedan and finds himself opposite that sport car -- well, the temptation is too strong to be resisted.

Tom's parental anxiety is a nuisance and an inconvenience, but there's no malice in the bureaucratic evasions that frustrate him. It's just the way this set of circumstances has evolved. Tom's problem is unprecedented and yet broadly appealing -- evoking an immediate, far-reaching sense of emotional involvement.

The movie sustains its tension through imaginative fidelity to the real world, and get its jolt from persistent, ironic shocks of recognition. Caan establishes this man's love for his missing kids with quiet but unquestionable sincerity -- and his search eventually ends in a scene of brilliantly restrained sentimental impact.

Along the way, Tom gets seriously involved with a teacher, Alisa -- very much Ruthie's opposite. When Alisa becomes pregnant, she and Tom marry, and there comes a time when his quest poses a threat to his new family.

Although it's obviously a shame that Tom should get less consideration from his government than a sleaze like Jack, the issues just aren't black-and-white. Sleazy Jack has his amiable, well-meaning side; and some of the law-enforcement guys sincerely feel for Tom and try to contrive a solution.

Given the willful social obliviousness of most American movies, it's novel fun to discover a movie in which the characters tend to recognize civilized constraints. It comes as a realistic stunner when Tom actually gets a lawyer. When that lawyer shows enough worldliness to seek out a reporter in order to solicit some helpful publicity, one feels astonished all over again. The people responsible for this movie truly respect reality and consider it a valuable dramatic resource.

A double triumph for Caan as star and director, "Hide in Plain Sight" also affords wonderful opportunities to a supporting cast of authenitic originals: Robert Viharo as Jack, Jill Eikenberry as Alisa, Barbra Rae as Ruthie, Kenneth MacMillan as a sympathetic detective named Sam Marzetta, Danny Aiello as Tom's lawyer and many, many others. A straightforward narrative melodrama of exceptional freshness, humor and generosity, "Hide in Plain Sight" looms as a formidable sleeper, potentially as popular as unifying inspirational hits like "Rocky" and "Kramer vs. Kramer."

It will deserve the popularity: This material puts down deep emotional roots while facing up to reality, a rare feat in contemporary American filmmaking.