Did anyone who saw Coram Boy think it needed to be more of a musical? It's possible that Australian writers James Millar and Peter Rutherford have never attended Helen Edmundson's hyper-theatrical adaptation of Jamila Gavin's novel anywhere it's played, but their musical The Hatpin suggests that on some level they believed it just didn't go far enough. The result is a musical that, while in some ways accomplished, is so unrelentingly bleak it makes Thrill Me: The Leopold and Loeb Story look like The Producers.

At its center is a homeless young mother named Amber Murray (Alexis Fishman), who wants her illegitimate son Horace to be properly cared for until she can raise the money to do it herself. An ad she places in a newspaper leads her to Charles and Agatha Makin (Paul Kandel and Cyrilla Baer, the latter fresh from her showstopping turn as Mrs. Zero in the expressionist musical Adding Machine), who promise to watch over the child in exchange for a modest weekly fee - but who, after taking her money, somehow are never willing to produce the child again when Amber asks. Uh oh.

Rutherford's music is usually of full-on operatic intensity, giving crowd scenes and most individual arias a weight of Sweeney Todd significance. Even so, it's practically impossible for The Hatpin to maintain suspense about what happened to Horace and why, which deflates much of Rutherford's success at establishing a ghoulishly Grand Guignol atmosphere.

Millar's book and lyrics and Kandel and Baer's markedly oozeworthy portrayals grant no shadings to either Makin - if you don't care about the villains, how can you care about the heroes? The couple's daughter Clara (Gemma-Ashley Kaplan, in a basically effective if overwrought rendering) fares somewhat better in relating to both Amber and her parents, but even she is treated for much of the show as a device of necessity, her by-the-numbers derision for her mother making her more of a mouthpiece for the audience than a person of her own.

Fishman sings capably as Amber, but finds little more than desperation in her, which is wearying over the long haul of the show. Caroline O'Connor, however, as Amber's newfound boss and friend Harriet, has real and varied feelings to play as both inspiration and avenging angel. Whether acting as mother, sister, or conduit between Amber and the outside world - including, in the show's tensest and most satisfying scene, Charles Makin - she's the only one who marshals the full range of human emotions (though her buck-up songs, with minor alterations, could be sung by the loving chambermaid Martha in the musical version of The Secret Garden).

Even director Kim Hardwick is satisfied with sounding a single discordant note, so swathing the show and performances in shadow that nothing ever has the chance to move into the light. This atmosphere becomes oppressive after a while, especially when three other women (Casey Erin Clark, Mary Catherine McDonald, and Sharone Halevy) who've been in Amber's position are introduced and do little more than wrap their black scarves around them as they vocalize.

It's possible all this could come jell as part of a fully integrated mood piece, but with the seriously suffering Amber and the caricaturish Makins, The Hatpin wavers too indecisively between tragedy and melodrama to allow that. The show is a fascinating glimpse into the Australian musical-theatre mindset, which in recent years has generally been seen in New York in much lighter incarnations (Prodigal, The Boy From Oz, and Virgins), if one that proves how the cohesion that defines the American musical at its best doesn't happen anywhere overnight.

Tickets online, Venue information, and Performance Schedule: The New York Musical Theatre Festival