"A Gentleman's Guide to Love and Murder” is less of a “whodunit” and more of a “he did it.”

The 2013 musical comedy, which nabbed a Tony for Best Musical, tells the story of Montague D'Ysquith Navarro (“Monty” to his friends), who discovers upon his mother’s death that he’s descended from royalty and ninth in succession to the title of Earl of Highhurst. Jobless, loveless and down on his luck, Monty hatches a murderous plan to rub out the eight heirs ahead of him and claim the title for himself.

Already extended through Feb. 10 at Le Petit Theatre, “A Gentleman’s Guide” stars Kevin Murphy as the criminally ambitious Monty, alongside Ricky Graham in a roguish, ribald performance as all eight of the D’Ysquith heirs—men and women alike. The refined, well-wrought production effectively marries drawing-room comedy with Broadway panache.

“A Gentleman’s Guide,” written by Robert L. Freedman and Steven Lutvak (and based on the 1907 novel “Israel Rank: The Autobiography of a Criminal” by Roy Horniman), begins at the end, with Monty in jail writing a memoir of his unexpected entrance into polite society and the clever killing spree that allowed him to rise through its ranks.

Kevin Murphy gives a commendable performance as Monty, staid and stoic on the exterior, but quick to reveal a sly wink or disclose a moment of wide-eyed panic to the audience, effectively recruiting the crowd into his conspiracy.

As a foil to Murphy’s straight-laced Monty, Ricky Graham hilariously hams it up, cycling through an assortment of short-lived characters that includes fops, dandies and blustering blowhards.

First act highlights include the witty staging of an ice-skating scene in “Poison in My Pocket” and the innuendo-laden number “Better With a Man.”

By the second act, Monty gets caught up in the complications of his plot, as he’s torn between two women: Sibella, the shameless social climber, and Phoebe, the blue-blooded maiden that could be Monty’s ticket to the top. As Sibella and Phoebe, Sarah Carlton and Rachel Looney excel in their supporting roles, particularly in the showstopper “I’ve Decided to Marry You.”

The remaining supporting cast — rounded out by Marie Bechnel, Tracey Collins, Bryce Slocumb, Matt Reed, Adam Segrave, Maggie Windler — is excellent as well.

The precise direction by Christina Pellegrini (who served as assistant director of the original Broadway production) keeps the action crisp and clear.

The cast sharply executes the stylish choreography of Polanco Jones, Jr., and musical director Michael McKelvey leads the orchestra with a deft touch

Turn-of-the-century costumes by Kaci Thomassie are elegant and bold, and one can only imagine the backstage magic required for Graham’s repeated quick changes.

The string of murders set up by the play’s premise sustains the forward momentum of the production, though the subplots — revolving around Monty’s romantic life and the backstory of his mother’s disinheritance — are less compelling. The energy of the show occasionally wanes when the story strays from Monty’s mission and from Graham’s portrayal of whichever D’Ysquith stands in the killer’s way.

In the end, “A Gentleman’s Guide,” like its title character, proves to be a polished production with a sharp wit and a glint of intrigue.

Brad Rhines writes about theater. Contact him at bradfordrhines@gmail.com.

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'A Gentleman's Guide to Love and Murder'

WHEN: Through Feb. 10

WHERE: Le Petit Theatre, 616 St. Peter St., New Orleans

Tickets: (504) 522-2081 or lepetittheatre.com