A password will be e-mailed to you.

We got a live one here, folks.

Gun & Powder is making its world premiere at Signature Theatre, but a betting woman would guess that won’t be the only place it plays. I’ve said it before and I’ll say it again: There are no good musicals with bad music. Well Gun & Powder has great music — and also believable characters, relevant themes, and, here at least, outstanding work from the cast and the pit.

Directed by Robert O’Hara and going on now until February 23, the show tells the story of Mary (Solea Pfeiffer) and Martha (Emmy Raver-Lampman) Clarke, two mixed-raced sisters living in 1890s Texas who pass as white while carrying out a string of wild-west style armed robberies. They’re sending money home to their sharecropping mother on a cotton farm, but along the way each gets tangled up with a man who wants more than she can give — and one of whom is rich and white. Dan Tracy’s Jesse is a gold-flashing rake charmed by Mary, while Donald Weaver Jr.’s Elijah is one of his servants who falls for Martha (and sees right through her disguise). Truth be told and spoilers withheld, that’s pretty much the whole story — the songs are more of the “exploring how we feel” variety than “moving the plot forward.”

Which is fine and dandy. With music by Ross Baum and lyrics from Angelica Chéri, these funny, moving, resounding numbers will stick with you long after the curtain call — which saw a huge standing ovation at press night. The tunes combine soul, jazz, West African, and Sondheim influences, and they give this abundantly gifted ensemble plenty to do. Playing the sisters’ mother, Marva Hicks simply pours herself into her stage time, and, as a pair of arched-brow maids who know what’s what, Yvette Monique Clark and Awa Sal Secka make their duet “Dangerous” the most hilarious moment of the night. A couple of the melodies bring to mind older songs — Mary’s “The Way I Am” ballad recalls “What Are You Doing the Rest of Your Life?” and Jesse’s angry epiphany number sounds more than a little like Sweeney Todd’s — but these feel like respectful echoes, not annoying derivations.

In their lead roles, both Pfeiffer and Raver-Lampman dig deep and soar high. When singing, they blend like a woven basket, but as actors they do a great job developing and showing personality in different ways. Everyone with whom they share the stage is terrific, too.

Complaints? I have but two: The second act drags a bit, particularly compared to the bustling first one; there’s space for some trimming ahead of the powerful all-hands-to-the-stage climax. And the cotton-sack set is boring, and no amount of projections can save it — at one point, the kaleidoscoping images of explosions (also why? there are no explosions in this play?) and women with revolvers makes one think of the opening credits of a Bond film.

But these are both things easy to correct in future productions, which, yeah, there should be. Though they might not have a costume and wig team clearly having the time of their lives, or musicians as clutch as these.

It’s such a rare thing to catch a quality musical at its debut; don’t miss this one.