The dealer, the telecoms magnate and the disappearing Stradivarius

Three years ago, the world-famous cellist Yo-Yo Ma accidentally left a 266-year-old cello worth $2.5m in the back of a New York taxi. Not long afterwards, a student at the Juillard School of Music, Meesun Hong, did the same thing with a $40,000 violin. In both cases, the instruments were speedily returned to their owners - a fact that speaks volumes about New York taxi drivers, and one that makes it all the more unfortunate that Christophe Landon, perhaps the city's leading Stradivarius dealer, was not riding in a yellow cab when he suffered his own violin-loss incident this year.

Even after a rigorous session of hypnosis, Landon cannot remember what he did with the instrument, a bona fide Strad worth at least $1.4m. All he knows is that it wasn't where he thought he had left it, in his workshop opposite the Lincoln Centre arts complex on Manhattan's Upper West Side.

Now the violin's owner, a Texan telecommunications magnate called Barrett Wissman, has announced that he is taking Landon to court, charging him with negligence. When I spoke to Landon this week, he was just about to fly to Dallas to be deposed by lawyers for the opposition, and things were tense, so I decided not to ask the obvious question: "Do you remember where you were when you last had it?"

There are about 650 surviving violins in the world made by Antonio Stradivari, and this uncertain figure became even more uncertain in April after Landon took seven or eight violins from his sealed vault and left them on a table for two customers to inspect. One was the 288-year-old, golden-brown instrument that he was trying to sell on behalf of Wissman. "And," he says, in his strong French accent, "I do not remember vividly putting it back into the vault."

There was no sign of a break-in; the police said the workshop's security systems had been functioning properly. One of the two customers has volunteered to take a lie-detector test, and Landon, getting desperate, consulted a hypnotist. "But it didn't work," he says. "I am not a good subject for hypnosis. It is very disappointing."

What must have happened, Landon says, is that he was robbed. The rarefied world of Stradivarius dealers is built on trust, he says, and someone betrayed his. "Kids are lent Strads, they go and have their concert, then they take them with them to dinner. Everyone is trusting. It was a setup." I ask him if he doesn't see Wissman's point, though. He counters that the $1.9m insurance payment that the entrepreneur had already received ought to have been enough. "Yet they are ready to draw blood," he says. Then he adds gravely, and very Frenchly: "It is the American way."

A few days ago, Wissman told the Dallas Morning News that he had been "distraught ever since it happened ... I entrusted the instrument to him [and] he was sloppy and negligent". The replacement value, he reckons, is nearer $4m than Landon's $1.4m valuation. Landon begs to differ. Actually, he doesn't really beg - instead he deploys the time-honoured alternative strategy for those accused of losing something valuable.

"That violin had a big hole in the middle of it, hidden under the touch-up, like if a Reubens had had the canvas replaced and touched up. And it sounded really bad. You know, that violin" - and here his voice falls in volume, and he says something that people do not, frankly, say very frequently where Strads are concerned - "it was a lemon."

· There is almost no limit to what you can do at an evening class in New York, thanks to the wondrous possibilities offered up daily by the Learning Annex, a hyperactive adult-education organisation whose catalogue is dispensed from yellow street-corner boxes around the city. Earlier this year, telepathy was on the menu, courtesy of a man describing himself as "Kreskin, the world's foremost mentalist". But in the coming weeks, a real crisis of choice is going to present itself, most obviously between "How to Be a Mystery Shopper" and "The Power of Shamanic Energy Healing" - although "Create a Miniature Shrine" is also tempting, as, for the more self-conscious new New Yorker, is "Lose Your Foreign Accent".

But the savviest advice, I suspect, is to be had from one Paul Mladjenovic, who leads a seminar priced at $59 per audience member. It's called "How to Become a $1,000-a-Day Seminar Leader". Ingenious.