There was a moment, back in the ’80s, when Nick Olcott learned what playwriting is all about. The 41-year-old author of Interact Theatre Company’s new musical, Sherlock Holmes and the Case of the Purloined Patience, a consciously frothy fusion of Sherlock Holmes mystery and Gilbert and Sullivan operetta, was still acting in those days. He was working with New Playwrights Theater, a company that used to produce new works and hold weekly play readings at Church Street Theater. The work at hand was, immortally, Phallacies, a somewhat troubled docudrama about the conflicts between Freud and Jung.

“I still remember the day the playwright came in,” Olcott says. “He had this wild-eyed look; he hadn’t slept all night, and he said, ‘I know how to fix the play. Take Page 33, rip it in half, move the bottom of the page to Page 24.’ So we took the script, chopped it up, reassembled it, and lo, it was a comedy. And that for me was just a revelation: I saw how material is crafted and shaped and comes to life, and what had been dull and dead suddenly was bursting with energy. It was the most exciting day of my career.”

The lesson has come in handy in the years since: Olcott has adapted Henry James (The Turn of the Screw and The Aspern Papers at Washington Stage Guild), John Steinbeck (The Pearl for a Kennedy Center touring production), and of course Gilbert and Sullivan (Interact’s Scottish Mikado last season and an HMS Pinafore set in Bermuda).

And he’s written original material, too. Among the quirkier items was a musical commissioned to commemorate Fairfax County’s 350th anniversary, which probably has the distinction of being the only stage work ever to encompass a marching song (originally written to a Kipling text) celebrating the building of the Beltway.

Now comes The Case of the Purloined Patience, the product of an inspiration that struck on the platform of a London tube station—the Baker Street stop, naturally. Olcott had decamped to England ostensibly on vacation, but a work-related question had been looming: What to do for Interact’s summer 1997 production, now that the company had run through most of the big Gilbert and Sullivan shows? The Gondoliers? An expanded, two-act Trial by Jury?

A glance up at the station wall, where a poster for a new production of the Mikado hung elbow to elbow with a silhouette of England’s most famous detective, and bing! Conan Doyle meets D’Oyly Carte.

“It came to me: Why not?” Olcott says. “They’re of the same era. They’re two of the best-known products of late-19th-century England.”

Though Olcott had directed the spoof Sherlock’s Last Case, he’d never been a Holmes fan, exactly. But he ran out to buy all the stories, and after he’d read them, he says, he was struck by the similarities—both in narrative formula and in subjects, content, and plot—that emerged when he considered Conan Doyle and G&S side by side.

“There’s always a young man who’s accused of a crime, and all the evidence is pointing at him, but he turns out to be someone else, and he’s somehow too good to be true. And there’s always a young woman with something to hide. And there’s always the class conflict: some upper-class person pretending to be lower-class, and vice versa.” Clearly, Olcott says, these were concerns of the era, issues that people talked about and that found expression in Conan Doyle’s stories and Gilbert and Sullivan’s shows.

“And what really fascinated me—and this came as a total surprise to me as I began to work on it—is that these recurring themes pop up in both—about what truly motivates people: love or greed. One is often hidden under the other.”

Olcott lifted a section of plot from The Boscomb Valley Affair, a Holmes yarn in which a young man seems to have killed his father for financial reasons (but is really innocent and can’t defend himself without betraying another’s secret). And he intertwined it with an outrageous story line inspired by a historical G&S curiosity.

“Pirates of Penzance had been such a huge hit on both sides of the ocean that when Patience was in rehearsal, copies of the score made it to this side of the Atlantic before it had even opened in London, and pirated productions began popping up in this country. I thought, well, if the London producers wanted to find out who was responsible for leaking the score, who would they hire but Sherlock Holmes?”

And so The Case of the Purloined Patience is both a play-within-a-play and a best-of-G&S revue. As opening night nears, London impresario Richard D’Oyly Carte learns of the unauthorized American productions and hires Holmes to get to the bottom of it. In classic Holmesian fashion, all the company members have motives. Rehearsals continue sporadically, so tunes like “Things Are Seldom What They Seem” and “I Am the Very Model of a Modern Major-General” (reworked so the singer is instead the epitome “of a crack Victorian super-sleuth”) turn up here and there. The affable Watson and the always irritable Inspector Lestrad turn up, but in the end, of course, it’s Holmes who unravels the truth, which naturally isn’t what anyone expected.

As if that’s not enough, Interact has landed Goodwill Industries chief Fred Grandy, fondly remembered as “Congressman Gopher,” to play D’Oyly Carte. (Kate Kiley, Tim Brierly, and Ralph Cosham are among the other principals.)

Olcott, who pleads utter ignorance of late-’70s/early-’80s television history, hasn’t a clue as to whether audiences will be able to get past Gopher to see D’Oyly Carte. But “I had written the character to be a stock figure, very much a martinet. I had not written him to be funny. Fred has made him very funny.”

Grandy insists he doesn’t mind if audiences see the ghost of his Love Boat past onstage beside D’Oyly Carte. “For me Gopher is a spirit but not a poltergeist. I live in the house that Gopher built.” Grandy learned a long time ago, he says, that you can either fight this kind of fame or make it work for you. “I rode it into Congress. It gets people to Goodwill’s annual dinners, and it’s part of why they called me for this role.”CP

Sherlock Holmes and the Case of the

Purloined Patience runs July 27-Aug. 31 at the

Folger Elizabethan Theatre, 201 E. Capitol St.

Call (703) 760-9863 for tickets.