Children of Nazis. Somehow that phrase seems a contradiction in terms, an incomprehensible merging of innocence and evil. Yet as you sit in your seat at Arena Stage, leafing through the program for "Born Guilty" -- Ari Roth's dramatization of Austrian journalist Peter Sichrovsky's interviews with the offspring of Nazi perpetrators -- you come across a full-page photograph, circa 1938, of a smiling, dimpled Joseph Goebbels, officially Hitler's minister for propaganda and public enlightenment, reading to his two flaxen-haired daughters. The image shocks and sears.

The stage is adorned with nothing but a spotlighted reel-to-reel tape recorder. Someone brings out a charming toy train on its track and sets it in the center of the space. Soon there are people -- ordinary, contemporary-looking folks -- milling about, carrying chairs and stools, a telephone, a wheelchair. A little blond boy in striped shirt and tie squats down to set the train in motion. His father joins him. Soon they're all watching the quaint locomotive chug and weave and, suddenly, burst into flames.

Blackout. Except for that hypnotic, parading blaze. This image, too, shocks and sears.

Strange as it may sound, those two potent visuals turn out to be the most troubling and effective touches of the entire enterprise. The photograph offers concrete proof of the unimaginable, while the burning train conjures up childhood-on-the-rocks, efficiency and madness, Bavarian villages and late-night deportations. For though "Born Guilty" addresses the horrors of the Holocaust and its legacy head-on, and though it offers a wide range of opinions and emotions, it rarely delivers the theatrical knockout punch that so provocative a subject demands.

The problem is first and foremost structural. In adapting Sichrovsky's book for the stage, Roth has made the journalist the central figure in the proceedings. Big mistake. Though perfectly affable, often amusing and certainly determined, the sight (and irritatingly literary sound) of the balding Sichrovsky (Henry Strozier) and his ever-present tape recorder do not make for gripping drama. Yes, the fact that he's Jewish lends a definite tension to the proceedings, but do we really need to hear him reminisce and relive his oh-so-'60s affair with Helga, a guilt-ridden hippie? Do his encounters with ultra-anal shopkeepers and rent-a-car agents really aid us in understanding the German mind-set?

Roth also seems to have had trouble deciding whether to present Sichrovsky's interview subjects as isolated individuals giving testimony or as characters in a play about generational conflict. The result is a script that veers back and forth between these approaches, and finally -- another big mistake -- settles on the latter. The most powerful moments come when the playwright just lets his characters vent, mourn, and -- most compelling of all -- simply remember.

"I saw a woman hit her child on the street and did nothing," declares Sibylle (Helen Carey), who wonders about her eerie lack of compassion.

"My grandmother actually met Hitler," the rebellious teenager Stefanie (Marissa Copeland) tells her classmates. "When he walked into a room, people jumped."

"We were an ordinary family," explains Anna (Copeland again). "As for crimes, camps -- the whole business was never mentioned." And later, after she discovers how skillfully her parents have covered up her father's criminal past: "Weren't these the same people who had fed me, clothed me, sat with me when I was sick?"

The 10 actors too -- all of whom play a multitude of characters -- are at their most commanding when allowed to speak directly to us. Each makes precise and memorable contributions, but standouts include Ralph Cosham's bewitching portrayal of the wealthy, nightmare-obsessed homosexual Rudolf, who calls himself "a child of dead monsters"; Carey's abused, scarily unfeeling Sibylle; and Pamela Nyberg's double turn as Sichrovsky's sarcastic ex-wife and Susanne, a guilt-ridden do-gooder of a mother/daughter.

This being Zelda Fichandler's directorial swan song at Arena, one would have liked "Born Guilty" to have proved a stronger showcase for her. Certainly she has imbued the production with her understanding of both the universal and the particular -- the characters shift cleverly back and forth between German and American accents, for instance -- and her uncluttered, at times crystalline staging allows the author's intent to shine through (for better and worse) at all times. Her finest touches, though, are purely visual: having a painter stick a frame around his frumpy mother, then sketch a skinny little Hitler mustache above her lip, or that powerful train sequence. No matter how momentous the material, it's those details that stay with us in the end.

Born Guilty, by Ari Roth, adapted from Peter Sichrovsky's book of the same name. Directed by Zelda Fichandler. Set, Douglas Stein; costumes, Noel Borden; lighting, Nancy Schertler; sound, Susan R. White. With Helen Carey, Marissa Copeland, Ralph Cosham, Jed Diamond, David Marks, Pamela Nyberg, Harold Perrineau Jr., Henry Strozier, John Leonard Thompson, Halo Wines. At Arena Stage through March 3.