Here is a mystery which would have whetted the appetite of Sherlock Holmes or, better still, Hercule Poirot, a man who truly appreciated haute cuisine.
Pascal Henry, 46, a Swiss motorbike courier, set out in May to eat in every Michelin three-starred restaurant in the world – 68 restaurants in nine countries in 68 days. He had reached restaurant number 40: El Bulli on the Costa Brava, acclaimed as the finest restaurant on earth, when, after his dessert, but before paying his bill, he vanished.
On his table he left his hat, some photographs and a notebook signed by some of the finest chefs in the world listing all the dishes that he had eaten so far.
That was just after midnight on 13 June. Since then nothing has been heard of him. His bookings in the remaining 28 restaurants have not been taken up. He was due to return to work this week. He has not appeared.
A missing persons search has been launched by Interpol at his uncle's request. One of the world's most celebrated chefs, Paul Bocuse, whose restaurant near Lyon was the first stop in Mr Henry's gastronomic marathon, has issued a personal appeal for information on his whereabouts.
"He couldn't just have vanished into thin air leaving his notebook," said M. Bocuse.
On 12 June, Mr Henry turned up on schedule for his meal at El Bulli. The restaurant claims to receive a million reservation requests each year. The average price of a meal is €230 (£180).
The Swiss foodie had completed his meal just after midnight when he struck up a conversation with a couple at the next table. According to the Catalan police, he reached into his jacket pocket to give them a visiting card and discovered that his wallet was missing. He asked for permission to go to his car to look for the wallet and never returned.
The police were alerted five hours later. They could find no trace of Mr Henry.
The tall, young-looking, bespectacled 46-year-old has a history of unexplained disappearances. While touring the United States as a young man, he vanished for several months. His estranged wife told the Swiss press that he was a secretive man. His uncle points out, however, that it is unlikely that he would have lightly abandoned a tour which had taken years of saving and months of planning.
Had Pascal Henry run out of money? Was his wallet stolen? Was he too embarrassed to go back to explain? Was he attacked? Did he fall from one of the nearby sea cliffs? "That would have been impossible," El Bulli's manager, Juli Soler, told the Tribune de Genève. "The restaurant terrace was packed. Someone would have seen or heard." Mr Henry began his tour on 5 May. He explained his plans to M. Bocuse, one of the great French chefs, who gave him a notebook and wrote down the menu that he had just eaten. He suggested that Mr Henry should ask each chef in each restaurant to do the same thing. M. Bocuse even promised to phone ahead and ask them to cooperate.
Mr Henry drove his car to other restaurants in France, Italy, Germany and the Netherlands. After his visit to Spain, he was due to fly to the United States and Japan before completing his tour at the Plaza Athénée in Paris, one of three three-star restaurants run by the French jet-set chef Alain Ducasse.
M. Bocuse, who was photographed with Mr Henry on the first night of his tour, said he was touched by his devotion to haute cuisine: "I wanted him to be welcomed warmly everywhere..."
He even telephoned El Bulli to ask them to help. "They seemed a bit irritated by the whole affair," he said. "They can't see that it has anything to do with them."
The world of Michelin's three-star dining is a place of elegance, exoticism and expense:
* The first Michelin guide, published in 1900 by André Michelin, showed drivers where to stay, where to service their car and – most importantly – where to eat.
* Michelin's first version was given away free and only covered France. Nowadays, the guides are seen as the ultimate authority on the finest dining worldwide. Michelin says it sells a million copies a year.
* A one-star establishment is seen as "a very good restaurant in its category"; two stars means "worth a detour"; and the sacred third star signifies "exceptional cuisine, worth a special journey".
* In 2007, Tokyo became the most starred city when Michelin distributed 191 stars among 150 restaurants – eight of them securing the maximum three. Paris has 98 stars in total, and London only 50.
* Three-star restaurants are not to everyone's taste. "There is an elaboration of food that you get in three star restaurants that – although it may be a magnificent mind-expanding experience – is rarely a comfortable one," says the food writer Charles Campion.