It's been a long time coming. I'm not talking about change, hope and a black president, though heaven knows we've waited too long for those. No, I'm talking about Apollo, Nancy Keystone's three-part epic play about Nazi scientists, NASA and the civil-rights movement, the final incarnation of which premiered last Friday at Portland Center Stage after eight years of development. In his curtain speech, PCS Artistic Director Chris Coleman mentioned an email from a patron who'd attended a preview and felt that the company "made the play three hours long just to irritate" her. It's actually closer to four, but it's worth it (though I'll forgive you if you leave after the second intermission).

Keystone, who also directs the show, has created a work that is unapologetically innovative, blending historical documents with fantasy, video projection and dance. In parts one and two, each of which has been produced before elsewhere, she explores the sinister origins of the U.S. space program in Werner von Braun's V-2 rocket research (fueled by the labor of concentration camp victims) and tells the story of Nazi-hunter Eli Rosenbaum's investigation of von Braun's partner in crime, Arthur Rudolph. These are mesmerizing, affecting works, with excellent writing and some of the finest moments of stagecraft I've ever witnessed. They are essential viewing.

But in part three ("Liberation") Keystone reaches too far, attempting to encompass the entire 150-year history of the civil-rights movement while sticking to the moonshot theme. Unlike the first two parts, "Liberation" lacks much in the way of strong characters or compelling stories. It's a mishmash, about a third of which is brilliant—most notably a scene that movingly compares the civil-rights volunteers to astronauts, venturing into the unknown at great risk to their lives. But the rest is of questionable merit and taste: the lengthy minstrelry number, in which black performers hogtie themselves, or the even lengthier, cartoonish re-enactment of George Wallace's forcible removal from the University of Alabama by the National Guard.

Documentary theater, like documentary film, is most successful when it illuminates the experiences of the many through the stories of a few. But "Liberation," lacking any single subject, fails to cast much light in the murk of America's shameful past of racial repression. Perhaps Keystone, who is white, felt daunted by the misery of the matter, and attempted to make the topic more palatable through humor. But this show doesn't need comic relief; it needs to lose half an hour. If Keystone had exercised a bit more discrimination in choosing her material, the final act might have been as compelling as the first two—and Coleman might be getting happier email.

Gerding Theater, 128 NW 11th Ave., 445-3700. 7:30 pm Tuesdays-Saturdays, 2 pm Sundays, noon Thursdays. Closes Feb. 8. $30-$66.50.