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Before Jayson Blair and The New York Times, there were Stephen Glass and The New Republic. It’s just that the earlier story about a journalist who fabricated stories and presented them as fact didn’t get quite the coverage the more recent episode has; and it did, after all, occur half a decade ago, which probably exceeds most people’s memory span (though Glass has recently re-emerged as a novelist, author of the roman a clef “The Fabulist,” about his own indiscretions). But while you await the inevitable docudrama about the Times’s debacle, you could do far worse than revisit the Glass affair through this sharp, observant recounting of it by writer-turned-director Billy Ray. “Shattered Glass” is a wonderfully understated treatment of the affair, a tragedy told sotto voce with a streak of mordant humor added to the mix. It’s a civilized film about civilized people caught up in an almost unbelievable situation, a happily non-didactic study of journalistic ethics that’s sort of the flip side of “All the President’s Men,” and in its quiet, unforced way it brings unexpected suspense to a tale that’s part of the historical record.

It also boasts a couple of superlative performances by Hayden Christensen as Glass and Peter Sarsgaard as Chuck Lane, the editor who was eventually compelled to confront his wayward writer. Christensen finally fulfills the promise of his early television work on the big screen; he makes up for the obligatory sullen teen routine of “Life as a House” and his inexpressive young Anakin Skywalker with a subtle, refined turn as a shyly likable, anxious-to-please fellow with an uncanny knack for fooling people. His boyish charm as he pads about the magazine’s office in stocking feet, making a point of complimenting colleagues and secretaries alike, helps to explain how Glass succeeded in snowing his superiors–including the late Michael Kelly, played with down-to-earth professionalism by Hank Azaria–for so long, even as the evidence of his transgressions mounted; and he turns Glass’s perpetually apologetic persona to humorous advantage. But Christensen, as canny as his performance is, couldn’t have made the film work in isolation; he needs rock-solid support, and Sarsgaard, a remarkable actor whose contributions to previous films (“Boys Don’t Cry,” for example) haven’t gotten the recognition they deserved–perhaps his turn in “K-9: The Widowmaker,” a picture so dull even he couldn’t shine in it, has been part of the problem–provides it. Sarsgaard gives Lane shading and depth, drawing a persuasive portrait of a man reluctantly thrown into the editorial position by the magazine’s publisher (Marty Peretz–an amusing cameo by Ted Kotcheff) and looked upon with suspicion by the staff, who must deal gingerly with personnel problems even when the circumstances are egregious. Christensen and Sarsgaard play off one another beautifully, without ever breaking the gently desperate mood. The rest of the cast serves them well enough, particularly Steve Zahn as the internet reporter who blows the whistle on Glass’s shenanigans, though Chloe Sevigny and Melanie Lynskey can’t do a great deal as two New Republic staffers whom Glass has charmed–the roles are underwritten and the motivations never explained. The film has a classy, simply elegant look and feel, and is edited down to an admirably clean hour-and-a-half.

There are lacunas in “Shattered Glass” that may disturb some viewers: the lack of any investigation into Glass’s background and motivation is the most notable. One may also quibble with the way the picture is structured, with scenes of Glass supposedly describing his work to an adoring class at his old high school alternating with the more straightforward presentation of the story. But while one might think that more, in the first instance, or less, in the second, might be preferable, the fact is that neither problem seriously undermines the effectiveness of the film. “Shattering Glass” will be useful as a cautionary tale, perhaps–indeed, as an examination of morality in the news business it’s scarier than any of the horror pictures out there this Halloween–but its real importance lies in the fact that it’s an absorbing drama that just happens to be based on real life. And that’s no lie.