It's a tricky business, time -- especially those fluid categories of past, present and future, flowing into each other before you can pin them down.

Even the past doesn't stay past, not when you inhabit it in your imagination or visit it via some sort of physical contraption, but of course that takes imagination, too.

One of the great time travelers was H.G. Wells (1866-1946), a father of science fiction, who's most famous for taking prophetic flights into the future but who played around with reverse trips, too. So who better than a young Wells to be the tweedy, bumbling hero of Karl Alexander's 1979 novel, "Time After Time," which that same year became a charming movie of the same title by Nicholas Meyer?

I have fond memories of that movie, starring Malcolm McDowell as Wells, Mary Steenburgen as his modern love interest, Amy, and David Warner as Dr. Stevenson, aka Jack the Ripper, let loose in 1979 San Francisco with murderous glee.

Now, in the tricky way of time travel, "Time After Time" has emerged as a new musical of the same name, having its world premiere at the Pittsburgh Playhouse, performed by the talented theater students of Point Park University.

Its creators are Stephen Cole (book and lyrics), a prolific writer of musicals that haven't yet conquered Broadway; Jeffrey Saver (music), a composer and music director of wide experience who teaches at Point Park; and busy director-choreographer Gabriel Barre.

Wells has developed a time-travel machine, and his friend, Stevenson/Ripper, uses it to escape the 1895 police and arrive, not in 1979 San Francisco, but in 2010 New York. There his tally of murdered prostitutes grows as Wells tries to catch up with the new horror he has inadvertently let loose on our world.

Call it "a good-old-fashioned-contemporary-sci-fi-romantic-thriller," as director Barre does in his program note. But much of our pleasure comes from the wit of the idealistic Wells' encounter with the future (our present), which he has to learn is no better than the world he left. Actually, given the terrors of late-Victorian London, it probably is better, but this isn't social history. Rather, it tweaks author Wells' belief in a coming utopia.

The opposition of eras is staged most dramatically through a chorus of ghosts, the Ripper's victims, who follow him from 1895 and are then augmented in 2010. These sequences, however creepy, along with a sympathy-begging flashback to the Ripper's rejection by his first love, promote him into a central role. He's even given a modern girlfriend, in parallel to Wells' Amy. I think this a mistake -- I don't really want to care about the Ripper's psychological problems, not when it takes so much focus from the charming Wells.

I feel that way about some of the songs, too, especially as the plot heats up in Act 2. Instead of advancing or intensifying the action, they put it on hold for an extra verse or two. Some details of the time machine stayed unclear to me, too, although my wife says it was perfectly clear to her.

More important, do Wells and Amy have to be such klutzes in falling victim to the Ripper? Feckless is appealing -- think Jimmy Stewart -- but it feels sloppy. There must be a better way to put them in peril.

That's what I'd like to see addressed in the further development "Time After Time" will certainly have. But they don't outweigh the many attractions that should give the musical a continued life.

There's plenty of wit in the details of cross-cultural encounters, often expressed in the lyrics, from naive discovery ("there's someone named Disney and he seems to run it all") to wordplay, as with the language of finance, in which "interest" serves several meanings. Above all, I enjoyed the clever use of the language and cliches of time -- almost to excess, but that's fun, too. My impression is that at least two-thirds of the songs use time as a theme, approached from many angles. This is intriguing stuff.

The music is of the modern "Jekyll and Hyde" variety, without its grandiosities. It's not melodic so much as atmospheric, with certain themes recurring to sustain character and plot.

Beyond the lead three, the rest of the creative team is local: Douglas Levine (music director), Stephanie Meyer-Staley (sets), Don Difonso (costumes), Andrew David Ostrowski (lights) and others.

The sets make good use of screens and projections, allowing a complex story to move quickly. The general stage decor is spare, with generic boxes for furniture, except for the time machine, a gorgeous expression of Victorian whimsy. Nothing is more admirable than a breathtaking opening tableau, and the lighting helps shape the busy story throughout.

It's a coup for Point Park to stage such a big, complex project so well, but the greater challenge is that posed to the student cast, who acquit themselves admirably. What a rare treat to be the first to play these roles, their talent feeding the process of further development.

I'm especially taken with John Wascavage's cranky, eccentric, ultimately endearing Wells. Michael Campayno's Stevenson/Ripper is richly melodramatic (with a delicious add-on in the curtain call), and Taylor Chalker is an Amy to care for.

There are others to praise in the huge cast of 30, but of course it's the brand new musical that is the center of attention. All concerned can be proud of what's been achieved so far.

First Published: March 8, 2010, 10:00 a.m.