There is a lot to be excited about in Lorene Cary’s My General Tubman, now at the Arden Theatre Company. Advance chatter has been electric. And at Wednesday’s official opening, producing artistic director Terrence J. Nolen announced that the production already has been extended through March 8.

There’s a lot that’s entertaining and worth seeing. You have history, bloodshed, heroism, love, and magic. You will frequently be charmed, as Wednesday night’s audience was, by a succession of surreal, moving scenes. The crowd murmured as local places were name-checked for their roles in Harriet Tubman’s Underground Railroad exploits.

But My General Tubman has a little too much going on. A good first act leads to a second act that loses momentum and focus. This hot property will continue to develop, find about 10 to 20 minutes it can profitably lose, and emerge even warmer.

Go, though. You have Tubman surging in popular culture, with several recent biographies, the film Harriet, and a sadly sidetracked campaign to get her on the $20 bill. You have as playwright the divine Lorene, one of Philly’s finest writers, a master of wise, poignant one-liners (“Staying alive isn’t as important as living right”). You have James Ijames, another of Philly’s finest, as director.

And you have Danielle Leneé, poised, stalwart, and visionary in the title role. She tells the men she leads, “A black woman gave you birth, and a black woman will steer you through time with love.”

In a sweeping overlay of fantasy and reality, Cary takes us from the Civil War to abolitionist Massachusetts to Canada to the 2020 Philadelphia penal system. Aaron Bell is a sprightly, Ariel-like Chorus (he reminds us, “Hey, it’s a play!”), and Brandon Pierce is Nelson Davis, Tubman’s worshipper through time and space.

Past and present have wild encounters. Our ancestors recruit us for their causes, save us from our worst selves — and we reach back and save them, too. A prisoner in a Philly jail in 2020 beholds a weary Tubman and gives her his socks and a foot rub. She actually gets into a car, exclaiming, “I love this buggy!”

The Philly jail scenes generally are more vivid, with more crackle, than those from the past. We meet Davis, along with Chaplain Ray (Dax Richardson, who tells Tubman, in a moment of giddy understanding, “Since it’s you, I feel irrationally sane.”)

Here, too, are Guard Claude, a troubled jailer played sensitively by Bowman Wright, and Earl Holloway, leader of the jail drumming circle (Damien J. Wallace, so droll he just about runs away with the show).

But we need the past, that amazing past, to crackle. Surely we need more tension in the subplot of John Brown. In act 2, his momentous, tragic decision to leave early for Harpers Ferry seems curiously blunted. Also in act 2, Tubman’s astounding leadership in the Combahee River Raid is too much told and not enough shown.

Nelson hits the central theme: that “we project her in our own image.” All of us, from Brown to Davis to Cary herself, have our personal General Tubmans. The question is: What are we ready to do with her, or better yet, for her? That’s a question each of us must answer — and a question that to some extent still remains for this promising play.

THEATER REVIEW

My General Tubman

Through March 8 at Arden Theatre, 40 N. 2nd St.

Tickets: $18-$53

Information: 215-922-1122, ardentheatre.org