It's hard to make a scary musical. What's meant to be chilling can sometimes come off as laughably overdone (think some iterations of Jekyll & Hyde), and creating that tension is often all for naught when a character opens his or her mouth to sing about their feelings.

Creep, the Jack the Ripper-inspired musical receiving its world premiere at WaterTower Theatre, manages to be spine-tingly and entertaining — some of the time.

The story, plotted by Dallasite Donald Fowler (who also penned the score), is at times a dark and brooding journey into the gutters of Victorian London. The depraved poor, trussed up like extras from The Rocky Horror Show, slither and slink through alleys and sewers, alternately trying to make a criminal living while staying one step ahead of a murderous killer's knife.

Floating above the grime is Mary (Sarah Elizabeth Smith), a girlish young woman who we learn used to be part of the city's lower class until her overbearing mother (Christia Mantzke) propelled them into society through mysterious means. An early flashback establishing the mother as a prostitute and Young Mary (Abby Chapman) as the victim of a horrid crime is murky at best and serves as the first of many moments in the show that almost, but not quite, make sense in the twisting tale that Fowler has concocted.

It's admirable that despite the holes and half-unraveled threads in the story director Kate Galvin has helped the characters emerge as richly drawn. Daniel Rowan is mesmerizing as Christian, Mary's wan piano teacher who operates under the patronage of Dr. Jackson Crowne (Jonathan Bragg). The two men have a history it seems, but even after several fervent and driving power ballads it's mostly unclear what has them so tortured. They're really passionate about ... something?

Not helpful in deciphering the plot is the stage's configuration, which buries the right side of the audience in an avalanche of sound from the hidden orchestra and cuts off sight lines for the left half. Jeff Schmidt's functional set is enhanced mostly by Jason Foster's lighting, which blots the actors like a bruise.

Derek Whitener and Victor Newman Brockwell must have bought every corset, cotton-candy wig, and pair of fishnet stockings in the Dallas-Fort Worth area for their steampunk-lite costumes, which transform the ensemble into a scuttling, menacing horde, as shiny and sleek as beetles.

The big story with Creep is that Fowler is not a trained musician, yet he composed the ambitious score with help from music director Kevin Gunter, orchestrator Dan Kazemi, and copyist Adam C. Wright.

The music is haunting and surprisingly melodic, with many standout tunes that run the gamut from the aching "Mothers and Daughters" to the bawdy tavern jig "Old Habits," sung with jolly chaos by Patty Breckenridge as a whore whose madness is becoming harder to ignore.

So where's Jack the Ripper in all this? He or she is there, lurking in the shadows, leaving bodies in the fog. To reveal who's brandishing the bloody knife in Fowler's retelling would spoil the genuinely startling ending, and sometimes it's more fun to just get lost in the atmosphere.