Daniela Mack Photo by Steven Pisano

The young American mezzo-soprano has been working steadily in-country and abroad over the last decade, essaying familiar roles (Carmen, Rosina, Sesto in La Clemenza di Tito) and creating new ones (she was Jackie Kennedy in the Houston premiere of David T. Little's JFK). Her Metropolitan Opera debut came earlier this year, in Dvorak's Rusalka—not as the sorceress Jezibaba or the cruelly enigmatic Foreign Princess, but in the minor trouser role of the Kitchen Boy. Yet, even with very few lines to sing, hers was instantly recognizable as an important voice; I recall listening to a broadcast at home and jolting up from the couch, astonished that the comprimaria was singing much of the principal cast off the stage.

Here, Mack takes on the title role in Elizabeth Cree, the third opera from Kevin Puts (music) and Mark Campbell, the Pulitzer Prize-winning team behind Silent Night (seen at Opera Philadelphia in 2013) and The Manchurian Candidate. It's a mammoth assignment, requiring flinty coloratura and headlong dives into the chest register over the opera's unbroken ninety minutes. Mack faces these challenges head-on. Her supple voice, wine-dark yet endlessly pliable, reminds the listener of Tatiana Troyanos in her prime; like Troyanos, she is also an unyieldingly committed actress, which serves her well in this varied role. We meet Elizabeth just as she's been sentenced to hang for her husband's murder; the opera then plunges us deep into the shadow-tinged world of late Victorian London, where Jack the Ripper and the music hall reigned supreme.

Puts, Campbell, and director David Schweitzer take their cues from that world; nearly every element of the piece is colored by theatricality. Elizabeth escapes poverty by becoming an accomplished vaudevillian, which allows for numerous pastiches of bawdy cockney songs. The characters speak in metaphors of the trade—a police detective (baritone Daniel Belcher, a company stalwart in terrific voice) on the trail of a serial murderer compares his press coverage to "bad notices." Even the fleeting scenes of Elizabeth's trial call to mind our current obsession with gavel-to-gavel coverage of salacious court cases.

But unlike Mack's triumphant performance, the opera as a whole achieves only fleeting success. The music hall numbers, though entertaining, largely fall flat. Unlike, say, Sondheim's Follies, which uses pastiche to probe its characters' psyches, these ditties often feel divorced from what's already a rather fragmentary narrative. The rest of Puts' unabashedly neoromantic score unspools like a movie soundtrack: lush, sometimes overwhelming, and largely forgettable. It often calls to mind the work of Samuel Barber, but again something is missing. Barber's Vanessa is similarly sonorous, but the arrestingly beautiful music stands in stark contrast to the deeply empty lives at the center of the story it tells. No such luck here.

Campbell's libretto falls prey to a real problem in modern opera: he often lets his characters narrate their lives to the audience, rather than interact with each other. In a work that's already short on narrative cohesion, this is doubly noticeable and problematic. But at least when the dramaturgy lags, we can relish Schweitzer's stunning physical production, with David Sinn's delicious sets and costumes, Alexander V. Nichols' steampunk-steeped lighting design, and inventive projections (also by Nichols) that manage to be eye-catching without intruding too much. Fine performances abound under the baton of Corrado Rovaris—baritone Troy Cook (as Elizabeth's doomed husband) and tenor Joseph Gaines (as a veteran Vaudevillian) deserve special mention—although the small chorus occasionally encountered problems with coordination at the performance I attended.

Above all, though, there's Mack, giving a performance for the ages. Whether or not this opera will be remembered remains to be seen, but one thing's for sure: this is a singer on the precipice of a major career. Catch her while you can.

Opera Philadelphia's production of Elizabeth Cree continues through Saturday, September 23, 2017, at the Kimmel Center's Perelman Theater, 300 S. Broad Street, Philadelphia. Tickets ($35-195) can be purchased online at operaphila.org.