“Eyewitness Blues” stumbles, but at least it stumbles in the right direction. That may be small consolation to some members of its audience at New York Theatre Workshop, who looked bored or bewildered by what they were seeing. (I was with them, here and there.) But there are larger forces at work behind the show, impulses that need encouraging. A little context may help.

Last night saw the opening of two off-Broadway musicals, “Dessa Rose” at Lincoln Center and “Eyewitness Blues” at NYTW. The former is the latest offering from Lynn Ahrens and Stephen Flaherty, the songwriting team that has sent “Once on This Island” and “Ragtime” to Broadway; a known and respected team around town. The latter was written by, and stars, Mildred Ruiz and Steven Sapp. They are founding members of Universes, the downtown poetry-music-theater collective best-known for “Slanguage.” I could see only one. Which one should it be?

You’ve guessed the answer, but it’s the getting there that matters. It has long seemed to me that if the musical theater has a future of any vitality whatsoever, it’s along the path being pursued (however fitfully) by artists like Mr. Sapp, Ms. Ruiz, and Universes. For all I know, the talented Ms. Ahrens and Mr. Flaherty might be the future of musical theater, too, of course. (Don’t miss my splendid colleague Helen Shaw’s review, left.) I mean only to say that, from what I’ve seen of Ms. Ruiz and Mr. Sapp’s work with Universes, they have a unique grasp of the chief trouble with musical theater today: There ought to be a connection between what we hear onstage in New York in 2005 and what we hear on the street in New York in 2005. Not many in their business seem to agree.

So as you’d expect, some moments in “Eyewitness Blues” have a lively, visceral energy. There aren’t enough of them, alas, not nearly enough (the show doesn’t hold together or “work” in any overarching sense) but they’re there, and they point towards what we might all be hearing in a few years’ time.

The main thing to understand about “Eyewitness Blues” is that Ms. Ruiz and Mr. Sapp have written a work of verse theater. Mr. Sapp, braids stretching down his back, plays Junior McCullough, a trumpet player who has “lost his breath.” With a big voice and flowing red costume, Ms. Ruiz plays his Muse – a combination of Virgil, Will Friedwald, and a good shrink – who leads him on a journey through his life story and some jazz history to find it.

The script comes unmistakably from the world of the poetry slam. In jagged or flowing bursts of verse, the Muse tells us that Junior was “born on the after beat,” and that an event in the distant past happened “many breaths ago.” Lovely, evocative lines like these recur throughout the show, but the script also suffers all the tics and preoccupations of poetry slams. The text is too often tricked out with literary brand names. “Last night I paid a visit to my good friend / Lorca who let me borrow his Duende / And Joe Campbell who showed me the map to finding Gabriel,” intones the Muse. Elsewhere, catchphrases crash together, as in this speech of Junior’s, where Miranda rights meet Melle Mel:

Gave up my right to remain silent So anything I say, can and will be held against me. . . So don’t push me, ’cause I’m close to the edge!

Uneven language might not hurt so much if the script had some kind of structure to keep everything moving. But neither the playwrights nor director Talvin Wilks supply it. The story tumbles back and forth to Junior’s childhood in the Bronx, to the travails of Bird and Miles, to fantasies about rolling in a crew with Wynton Marsalis. Nothing seems to be at stake for Junior or his Muse. The show feels much longer than its 85 minutes.

But this is also – and here is the other thing to note – a work of musical theater. Ms. Ruiz and Mr. Sapp are joined by a pair of trumpet players (Antoine Drye and Paul Jonathan Thompson, who composed original music with Carlos Pimentel). Sometimes they break into sharp imitations of Louis Armstrong and Miles Davis, elsewhere Ms. Ruiz joins them in song. The best thing in the show is a trumpet duet, with Ms. Ruiz singing, and Mr. Sapp dancing and keeping time with his feet. The story may not be going anywhere, but bright theatricality is bright theatricality, and that moment has it. (It helps that, for the third time this season, NYTW shows its subscribers a new face. Covered in drywall for “Hedda Gabler,” turned into an operating theater for “A Number,” the rectangular space has now been transformed by Narelle Sissons into a runway, with tall mirrors and red curtains on the walls.)

The show’s scattered poetic and musical highlights may leave you longing for the one kind of theater that combines verse and music in the same thrilling beats: hip-hop. It’s the most exciting thing happening in American theater today. Or, alas, not happening, as there haven’t been many visible advances after the burst of activity a few years ago. But there’s good news to report. A spokesperson for NYTW tells me that Will Power’s “The Seven,” a hip-hop adaptation of Aeschylus’s “Seven Against Thebes,” is aiming to be in the lineup next season. Even better: Jo Bonney, one of the steadiest hands in town, will direct.

Even as you wish that “Eyewitness Blues” had turned out more cohesively than it did, NYTW deserves credit for supporting artists like Ms. Ruiz, Mr. Sapp, and Will Power. As for everyone else in town, here’s hoping they follow soon. If Joe Papp were alive, he’d have rappers everywhere.

Until April 10 (79 E. Fourth Street, between Bowery and Second Avenue, 212-460-5475).