Long before the public meltdown became a reliable vehicle for celebrities seeking renewed attention and sympathy, there was one Oscar Levant, who made his name as a brilliant pianist but became almost as well known for his acerbic, sometimes controversial wit and, later, his psychological struggles. Those facets were all on display during a 1958 appearance on “The Tonight Show,” during which Levant, shooting the breeze with host Jack Paar, discussed his depression, chemical addictions, and even the electroshock treatments he endured.  

That episode, which generated its own shock waves at the time, provided the inspiration for Doug Wright’s “Good Night, Oscar,” a simultaneously flamboyant and earnest comedy that arrives on Broadway after an acclaimed run at Chicago’s Goodman Theatre. Directed with a rather heavy hand by Lisa Peterson, the production casts stage and screen star Sean Hayes, last seen here in the more genuinely outrageous and irreverent “Act of God,” as Levant, whom we first meet as he is barreling into a dressing room on the “Tonight Show” set.

Having been granted a four-hour release from the mental hospital where his wife, June, had him committed, Levant is accompanied by a young medical orderly who’s as serious as the heart attack that was reportedly instrumental in getting him hooked on Demerol years earlier. By this point, we have watched Paar, whose own accessibly erudite presence and humor are captured by a razor-sharp Ben Rappaport, argue passionately in favor of his chosen guest’s appearance on the show to the wary network chief, Bob Sarnoff, played here as a corporate coward by a convincingly square Peter Grosz.

Sarnoff isn’t even aware, initially, of Levant’s temporary outpatient status; still, his reluctance to put Levant on live television isn’t entirely unwarranted. As Mr. Hayes presents him, Paar’s favored guest is all nerves and tics; as he rocks back and forth, hands shaking, we’re hardly surprised that he keeps begging for the soothing drugs the orderly keeps scrupulously stored away in a large briefcase. 

In particular, Levant is haunted here by the memory and legacy of his friend George Gershwin, who appears as a somewhat smug ghost, played by a dashing John Zdrojeski. While Levant was himself a composer — his credits include the standard “Blame it On My Youth,” as well as a classical piece that impressed Aaron Copland — his talents in this arena were obviously dwarfed by those of his buddy, and accounts of Levant’s life tell us it was both a blessing and a curse that he became a leading interpreter of Gershwin’s work long after the latter’s untimely death.

The most melodramatic segments in “Good Night,” in fact, find Levant driven to physical, almost hallucinatory agony as excerpts from “Rhapsody in Blue” thunder exquisitely in his head. (We hear them too, happily — and Mr. Hayes himself plays a generous portion at one point, with effusive virtuosity.) “From the grave, George did me a horrible favor,” Levant laments in a more lucid moment, then adds, “I gave up living my own life, so I could be a footnote in his.”

June, who’s played by an elegant Emily Bergl, is assigned some similarly stilted speechifying on her husband’s behalf. “You don’t book a zebra, then bitch about its stripes,” she lectures Paar, after he and Sarnoff try to preemptively censor Levant’s on-air repartee. “Oscar’s forever slipping on banana peels, so we don’t have to,” she continues. “‘There but for the grace of God go I.’ That’s more than sacrifice, gentlemen. It’s blood-letting.”

That little sermon is followed by what is by far the play’s most briskly entertaining scene, in which Mr. Wright’s own comedic gifts are buttressed by those of Levant and Paar, and Messrs. Hayes and Rappaport, as the playwright and actors revisit that famously frisky, feather-ruffling exchange that caused such a stir more than 60 years ago. 

“One of the joys of live television is its unpredictability,” Paar reassures his audience. That may no longer be true as often as it once was, but “Good Night, Oscar,” at its best, transcends nostalgia to make a case for the enduring powers of creative courage.