Kristin Chenoweth leads ‘On the Twentieth Century’ to theatrical bliss

“They don’t write dialogue like this anymore,” a producer says, leafing through the Bible in “On the Twentieth Century.” And they don’t write musical comedies like this anymore, either. Gloriously revived by the Roundabout Theatre Company, this 1978 musical — now with sparkling turns by Kristin Chenoweth and Peter Gallagher — is a fast-paced romp.

Set entirely on the 20th Century Limited train from Chicago to New York, the show — music by Cy Coleman, book and lyrics by Betty Comden and Adolph Green — barrels down the tracks to theatrical bliss.

Chenoweth plays Lily Garland, the movie star whom Oscar Jaffee, Gallagher’s down-on-his-luck producer, sees as his ticket back to the big time. Having transformed her from a mousy backup pianist named Mildred Plotka into a glamorous Hollywood diva, Oscar thinks she owes him.

Along for the ride are Andy Karl as Bruce Granit, Lily’s vainglorious actor lover, and Mary Louise Wilson as Letitia Primrose, a millionaire and owner of that Bible, who’s set to bankroll Oscar’s new show, about the life of Mary Magdalene.

Comden and Green, whose classic musical “On the Town” is playing just a few doors down, did some of their best work here. And Coleman’s jazzy, operetta-style score, featuring one of the most joyous overtures ever to be heard on Broadway, is sublime.

From harmonizing and tap-dancing porters to elaborately staged numbers and many bits of physical comedy in between, the show is a nonstop delight. Director Scott Ellis — succeeding the great Harold Prince, who directed the original production starring Madeline Kahn, John Cullum, Imogene Coca and the not-yet-famous Kevin Kline — never once lets the pace lag.

Chenoweth uses her whippet-thin body and multioctave vocal range to delicious comic effect. Gallagher — his plummy voice recovered from the infection that forced him to miss several performances — delivers a terrifically entertaining, outsize turn as the melodramatic Oscar.

Just as fine is the cast that surrounds them. Karl, who hasn’t lost the muscles he built for Broadway’s “Rocky,” does push-ups with Chenoweth perched on his back, while Wilson — age 83 — is a hilarious and dynamic Mrs. Primrose. As Jaffee’s loyal underlings, Michael McGrath and Mark Linn-Baker never miss a laugh.

The show looks gorgeous, too, thanks to David Rockwell’s glamorous art deco-style sets and William Ivey Long’s period-perfect costumes.

All told, “On the Twentieth Century” is on track to score big at Tony Awards time — Chenoweth might as well start practicing her acceptance speech. Buy your tickets before the train leaves the station.