BANGKOK - At a bend in a busy Bangkok road stands the Tree of 100 Corpses, a shrine to pedestrians who have died in traffic accidents nearby.

People come from all over Thailand to commune with spirits they believe reside in the tree. They also come to find winning lottery numbers.

"I made a wish to the tree and asked that the number pop up in my dream," said Kriengsak Konart, a motorcycle taxi driver. The number 45 came to him in his sleep, he said, and he played a variation of it.

"I won," he said.

Many Thais believe that calamity can beget good fortune, and that tragedy may give rise to powerful ghosts who offer guidance on winning numbers. Newspapers report the license plate numbers of cars involved in gruesome accidents. Lottery aficionados note the highway route numbers where accidents took place, tally the casualties and play the numbers. Nothing is seen as too horrible to be a source of good luck, not plane crashes or massacres.

The search for numbers to play in Thailand's illegal but tolerated lottery is a national obsession, culminating twice a month in the drawing of plastic balls to decide the winners.

People play numbers that occur to them in dreams, or the numbers of the hotel rooms where movie stars stay, or the prime minister's birthday. But many believe the best numbers come from powerful ghosts, those who have endured terrible pain or suffering.

One of the country's most famous ghosts is Mae Nak, who is honored at a shrine in southeastern Bangkok. According to Thai legend, Mae Nak died in childbirth while her husband, a soldier, was on a military campaign.

Paan Padthong, 72, a fortune teller who works near the shrine, said: "If you are someone who possesses good luck, all you have to do is step into the shrine and you will start to see numbers."

Like many countries, Thailand has an official state-sponsored lottery, but the underground lottery is much more popular: nearly one-third of the population play it, partly because the chances of winning are better, at 1 in 100. The main official prize is much larger, but the odds are 1 in 1 million.

The unofficial lottery is part of the vast Thai underground economy. It is also a rich source of petty corruption: Noppanant Wannathepsakul, an academic who researched the lottery, estimates that the police get 11 billion baht, or $362 million, in bribes and protection money from the underground lottery every year.

For a symbol of the collusion, it is hard to beat a shrine in the Chinatown neighborhood of Bangkok, where Yee Hoh Kong, one of the 19th-century pioneers of the Thai lottery, once lived.

The shrine, one of the most popular places to seek guidance for numbers, is on the fourth floor of a police station.

"Not many people come here to report a crime," said Thassana Pleuangcharoen, a police officer who greets visitors. "Most come for the shrine."

Giulio Di Sturco for the International Herald Tribune

Many visitors to the shrine to Mae Nak, one of Thailand's most famous ghosts, are keen lottery players.

Thais believe that tragedies beget the luckiest numbers.

Giulio Di Sturco for the International Herald Tribune

The Tree of 100 Corpses is an inspirational spot in Bangkok for those trying to dream up winning numbers in the underground lottery.

The New York Times