In Amy Herzog's "After the Revolution" at Theater J, an activist family's secrets revealed The twist: It's about to become grim public knowledge that this family "hero" passed secrets to the Soviets. The time is 1999, and Herzog is drawing from the real-life revelations then coming to light about U.S. anti-Soviet snooping via the Venona Project. Worse: Ben, Emma's father, an almost preposterously fervent Marxist, has known about the spying forever, yet he withheld this information from his idealistic daughter. Herzog has generated a lot of buzz as one of the country's brightest playwrights, and "After the Revolution" shows why. Her crisp "4000 Miles" at the Studio Theatre a few months ago dealt with members of this same clan, and in both plays, the personal bleeds into the political. Convictions run deep, yet Herzog almost effortlessly shows how events can upend even bedrock beliefs. It can be hard, can't it? Emma's wealthy patron says at one point. Even for very bright, well-meaning people, in a tough situation, to know what's right. The recognition that rippled through Theater J on Wednesday night was like a murmured "Amen." Emma is the centerpiece; everything filters through this young idealist, and Megan Anderson's performance is wonderfully fiery and fragile. Anderson wears the politics easily as Emma begins to question the purity of her foundation, which is crusading on behalf of Mumia Abu-Jamal. That long-running controversy dates back to Jamal's 1982 conviction for shooting a Philadelphia police officer; Jamal's advocates have claimed the trial was unfair. Emma has been thinking Jamal, a former Black Panther, was persecuted for his beliefs . . . just like her Communist grandfather in the 1950s. Anderson also deftly handles Emma's psychodrama with her father Ben, an ever-pained bleeding-heart liberal. Ben is almost a lampoon: "You made me call my Walkman a Walkperson," Emma says, complaining of her dad's long-standing overkill of political correctness. Herzog lets the audience laugh at Ben, but she also lets him make his case. Peter Birkenhead is terrific at showing both the pathetic underbelly and noble intentions of this entirely recognizable figure. As the arguments unspool, you appreciate the soft quality of director Eleanor Holdridge's approach. The play shoots out of the gate like an excited horse, but it slows down and listens as Emma gingerly quarrels with her boyfriend, Miguel (serenely played by Carlos Saldaña), frets with her wise, old benefactor Morty (a quietly jolly James Slaughter), and absorbs a personal history lesson from her stepmother, Mel (warmly played by Susan Rome). Jeff Allin, playing Ben's brother, Leo, is as cool as Birkenhead's Ben can be hot, and Elizabeth Jernigan offers an understated turn as Emma's fresh-out-of-rehab sister. And as the grandmother, Vera - fleshed out into a real showcase role for Herzog's later "4000 Miles" - Nancy Robinette miraculously manages to be gentle and yet the most unyielding figure in the play. Herzog knows these people inside and out: Both plays have wide autobiographical streaks, and she's done her research. A giant red curtain looms across the back of Misha Kachman's set, and as the characters hash out everything from the Depression and Stalin to who's keeping secrets now, you understand that for the fascinating Joseph clan, neither politics nor the past is ever really out of sight. After the Revolution by Amy Herzog. Directed by Eleanor Holdridge. Lights, Andrew Cissna; costumes, Kendra Rai; sound design, Patrick Calhoun; composer, Matthew M. Nielson. About two hours. Through Oct. 6 at the D.C. Jewish Community Center's Goldman Theater, 1529 16th St. NW. Call 800-494-8497 or visit boxofficetickets .com.