Musicology and melodrama mesh uneasily in "33 Variations," a new play by Moises Kaufman that marks Jane Fonda's return to Broadway after a mere 46-year hiatus. The tale of a music historian's obsession with a mystery involving Beethoven is pretty thin, but audience affection for its iconic star could result in solid business for its limited run.

Fonda plays Dr. Katherine Brandt, a music historian desperate to uncover the reason the great composer spent his final years composing a staggering 33 variations on a simple, minutelong waltz written by a Viennese music publisher as a publicity stunt.

She thus travels to Bonn, where she examines Beethoven's original manuscripts under the watchful eye of a sardonic archivist (Susan Kellermann). There's an urgency to her quest because she has a degenerative nerve disease that soon will prove fatal.

Running subplots involve Katherine's tense relationship with her restless daughter, Clara (Samantha Mathis), and Clara's burgeoning relationship with Mike (Colin Hanks), a sweet nurse.

Interspersed with action set in the present are scenes from 1819-23 in which we see a crotchety Beethoven (Zach Grenier), struggling with ill health and deafness, interacting with his loyal assistant (Erik Steele) and the waltz's composer, Anton Diabelli (Don Amendolia), who can't believe his luck.

The play, which Kaufman describes as "a series of variations on a moment in a life," is most successful in its exploration of a fascinating episode in music history, with pianist Diane Walsh playing numerous excerpts from the work in question on a grand piano at the foot of the stage.

The dramatic elements — such as Katherine's increasingly desperate struggle with illness and Clara and Mike's awkward courtship — are far less interesting, though the scenes involving Beethoven have an undeniably arresting "Amadeus"-like quality.

The many years since Fonda's previous stage work have taken a toll, with the star often seeming even stiffer than her increasingly physically challenged character. Because her role basically is reactive, she doesn't have much to play, and it's hard not to wish she had chosen a more effective vehicle for her return to the theater.

Hanks and Mathis are appealing as the young lovers, but their cutesy interactions are more distracting than entertaining.

Kaufman, who also directs, provides nice touches in the staging, including a charming, climactic minuet danced by the ensemble. Unfortunately, they're not enough to rescue a play that could have used some of Beethoven's genius to produce more compelling variations on a slight theme. (partialdiff)