NEW YORK – Worthy theater sometimes slips away without ever finding its core audience. The Morini Strad, a two-hander presented by Primary Stages through April 28, could be an example.

Even for sophisticated off-Broadway audiences, the title isn't likely to ring any bells.But mention it to any of the older Philadelphia Orchestra violinists and they'll snap to attention. The Morini Stradivarius still comes up in conversation some 15 years after it vanished while its owner, the great violinist Erica Morini, languished near death in a nearby Manhattan hospital, having kept the instrument under lock and key over her 19-year retirement. She died in 1995, at 91.

Though characterized by playwright Willy Holtzman as a forgotten woman, Morini still has more than a cult following: Not only are her live performances being released for the first time on labels such as Arbiter and Audite, but an 11-CD set of her studio recordings titled "The Art of Erica Morini" sells for $599 on Amazon.com marketplace. She had a particularly consistent bond with longtime Philadelphia Orchestra music director Eugene Ormandy. During the 1950s, she was an annual fixture at Robin Hood Dell. Once heard, she was not easily forgotten.

Her stage incarnation tends to intersect with Driving Miss Daisy: A cranky old woman sparring with a younger man in her service. In this case, it's Brian Skarstad, a violin maker she brought in to do minor repairs on her instrument, then called the Davidoff Strad, made in 1727, in Antonio Stradivarius' late and best period.

While making plans to sell the instrument (which she ultimately decided against), she comes out of her cantankerous shell in a character study about the price of being a great artist and then coping with life after artistry is no longer possible.

Though written in close consultation with the real-life Skarstad, The Morini Strad plays with the facts. At one point, the Vienna-born Jewish violinist confesses that "Morini" was only a stage name, which is not true. Much is made of her child-prodigy years, though the adult Morini had little trouble with the stunted artistic development that often comes with that. She seems utterly reclusive t the end of her life; had that truly been the case perhaps there would have been no awareness that the violin was there to steal.

Sometimes the Morini character slips into the Auntie Mame zone: At one point, she claims life is a symphony and the best part is the scherzo.

Much of the play, though, has great poetic truth. The sense of pride that is so well-explored in the play and that allowed her play in the world's great concert halls also hastened her real-life retirement in 1976: She was incensed when – after the arrival of such hot young violinists as Pinchas Zukerman and Itzhak Perlman – she was offered reduced fees (also, perhaps, because she was a woman).

Her obsessive attachment to the instrument is typical of those who find that their violin gives them their voice and becomes part of their inner identity. (Once when I jokingly asked Hilary Hahn if she hired a babysitter to guard her violin, she replied, half seriously, "It hasn't come to that.")

The violin is a harsh mistress. Strings and fingerboard are so small and require precision beyond the comprehension of most mortals. As played by Mary Beth Peil with great dimension and off-hand humor, Morini emerges as someone who held herself to such an Olympian standard for so much of her life that she can't help but turn her back on the world in widowhood and retirement. She comes off not as an alienated person who fears the world but as someone who doesn't see much reason to go out into it.

Morini was considered the equal of violinists who are now legendary. What the play deals with, only lightly, is why isn't she, too, a legend?

One repeating pattern in her career is intense relationships with institutions that weren't sustained. In her recording life, for example, she departed from RCA just as the LP was coming in. Thereafter, she recorded with B-level labels such as Westminster and American Decca that died before the arrival of the compact disc. She made a single recording for the prestigious Deutsche Grammophon label; plans for more ended with the 1963 death of her collaborator, conductor Ferenc Fricsay.

Morini also seemed to have burned bridges. "D'ya think?" said the real life Skarstad in a phone interview this week. Though he grew to like her, he said, he heard nothing but reports of her harshness.

The bigger question is what happened to the Strad. Just because Morini was paranoid doesn't mean people weren't after her possessions. And the violin wasn't very stored in a closet that could be opened with a skeleton key, said Skarstad.

While Morini was in the hospital, a plumbing leak flooded her apartment. Might her valuables have been removed for safe keeping, and then stolen? Besides the violin, many personal papers dating back to the time of Brahms also disappeared. Skarstad was briefly considered a suspect. Grand jury investigations were held.

Who would be foolish enough to steal such a well-known violin? Though valued at $3 million, the instrument couldn't be unloaded easily — or for anything close to that sum.

But money may not have been the point. The Strad now played by Joshua Bell was stolen from Bronislaw Huberman backstage at Carnegie Hall in 1936 and was missing until 1985, when a little-known violinist named Julian Altman confessed the theft to his wife on his deathbed. He had played it for half a century.

Morini never learned the fate of her violin. "There was no point in telling her," said Skarstad. "Why end her life like that?"

But by no means is the story over. As one FBI agent told Skarstad, "I'm a very patient man."

Primary Stages' 'The Morini Strad' is at 59E59 Theaters, 59 E. 59th St., New York. Information: 212-279-4200 or www.ticketcentral.com.

Contact music critic David Patrick Stearns at dstearns@phillynews.com