Cynthia D. Barker (as Sal) and Anthony Manough (Ossie) in “Uprising” at MetroStage in Alexandria. (Chris Banks)

In her poetic and music-rich fable “Uprising,” playwright Gabrielle Fulton explores a little-known corner of American history with much heart and mixed success. She interlaces fact, fiction and her own family’s ancestral tales to fashion a story about free African Americans living dangerously near the world of slavery, just before the Civil War.

The emotional, fast-moving production at MetroStage often succeeds in blending the charm of a traditional folk tale with the power of a moral polemic. When the show falters, it’s because of a lapse in clarity — in Fulton’s blend of history and fiction, or Thomas W. Jones II’s direction, or both.

This is a new play, produced at MetroStage as part of a rolling world premiere that began in July at Horizon Theatre in Atlanta. The director and three of the actors, Cynthia D. Barker, Enoch King and Anthony Manough, had the same roles in the Atlanta production. The play also is part of the Women’s Voices Theater Festival. So the piece is still aborning, in a sense, and there’s time to tinker.

The philosophical tug of war at the core of “Uprising” feels raw today, although it’s set in October 1859 — whether to foment a violent revolution against slavery or seek one’s own freedom and that of one’s family and stay safe.

Characters interact with explosive consequences on Robbie Hayes’s set of rough-hewn planking. Projections (also by Hayes) on a backdrop vividly set the scenes — in a field, an 1850s slave market, on a muddy Philadelphia street.

Sal (Barker), a free black woman, picks cotton for wages at a plantation in Pennsylvania. A strong woman, she outdoes the men in her daily cotton totals. She also talks to the birds and lovingly raises an adopted little boy, Freddie (Jeremiah Hasty).

Working in the field one day, Sal encounters a fugitive black man — the charismatic Ossie (Manough), based on the real-life Osborne Perry Anderson. Ossie is not an escaped slave; Anderson was a free black man who participated in John Brown’s 1859 raid on the federal arsenal at Harpers Ferry, Va. (now West Virginia), narrowly escaping capture.

Not only is Sal romantically drawn to this handsome, educated man, but she also is torn nearly apart by his insistence that she run away with him and work to overthrow slavery. Once her boss at the plantation (Peter Boyer) learns of the raid at nearby Harpers Ferry, he sets a curfew. Sal’s friends and co-workers (including King, Roz White and Doug Brown) view Ossie with dread.

Ossie keeps courting Sal and, in a calamitous move, gives little Freddie a gift that gets the child into terrible trouble. The second act centers on Ossie, Sal and a white abolitionist (Boyer) in Philadelphia as they work to save the boy.

The musical element adds many emotional grace notes. The show isn’t exactly a musical, but it is more than a “play with music.” The songs — some classic blues tunes, some spirituals, some newly penned in the old style by Theodis Ealey with his or the playwright’s lyrics — pass in quick fragments. And although the new songs lack the power of the old ones, the full list gives the play a kind of second heartbeat, helped along by guitarist/singer David Cole, who wanders the stage as the itinerant Tuneman, commenting musically on the action.

Although it feels like a project as yet unfinished, “Uprising” galvanizes big ideas and feelings, which is half the battle.

Horwitz is a freelance writer.

Uprising by Gabrielle Fulton. Part of the Women’s Voices Theater Festival. Directed by Thomas W. Jones II. Music direction by William Knowles. Costume design, Janine Sunday; lighting, Alexander Keen; sound, Roni Lancaster and Thom Jenkins. About 2 hours 15 minutes. Tickets: $55-$60. Through Oct. 25 at MetroStage, 1201 N. Royal St., Alexandria. Call 703-548-9044 or go to www.metrostage.org.