Walking through the narrow, crowded lanes leading to the Khar Road Railway Station in suburban Mumbai, we approach a nondescript, three-storey building.
From the outside, nothing seems unusual about the place. It is dull, with a fading coat of colour. Inside, the stairs are dark and dingy, and it is difficult to notice the camera hanging from the ceiling on the second floor.
As we stand at a door, our friend takes out his mobile phone and makes a call. The door opens, a brief introduction is made, and we are ushered into a room where three men are busy answering the seven mobile phones lying on the table in front of them.
There is little else in the room - except for three LCD monitors showing the live telecast of India's first Test against Australia in Mohali.
"Business is not bad," the man in charge says. "As you can see, the calls never stop. Some days, we can get as many as 2,000 of them. When our game [India] is on, we don't even have time to use the bathroom."
It is the fourth day of the Test match and the odds fluctuate wildly for both teams. The men are working almost non-stop.
"This is a really tight game," says the leader, who asks to be called Kiranbhai (not his real name). "In such matches, people usually place seven or eight different bets to increase the chances of their winning or mitigate their losses."
Kiranbhai is one of scores of mid-level bookmakers in Mumbai, the hub of illegal cricket betting. More than 2,000 illegal bookies are believed to operate in the city, and the odds for matches are set here and circulated to illegal betting shops around the world.
It is estimated that several billion dollars a year are wagered on cricket, and authorities allege that much of it is handled by a vast crime syndicate controlled by Dawood Ibrahim, a former Mumbai businessman who is ranked as the fourth most wanted criminal in the world by Forbes magazine.
Authorities believe his organisation - called the "D Company" - controls cricket betting and other illegal activities in several countries, including India, Pakistan, South Africa and England. Bookmakers in those countries allegedly report to bosses in Mumbai.
It is a flourishing but secretive business; the bookmakers never indulge strangers. In Kiranbhai's operation, every caller is known to the four men in the room - they have met in person, or an "insider" has vouched for them, such as the friend who made our introduction.
Elite customers are given a direct line - a mobile phone and a SIM card that allows them to place bets from anywhere in the world. Almost all bets are placed through mobile phones.
The conversations between bookies and clients are brief and are often recorded by both sides to serve as proof in case of a dispute. Kiranbhai allows us to listen to one such recording.
"Thirty-six pe ek peti khaya," says the man at the other end. The words are repeated by the bookie as confirmation, and the call is over in a matter of seconds.
Translation: the punter has bet 100,000 Indian rupees (Dh8,300) on fewer than 36 runs being scored in a 15-over session of the Test.
This is called spot-betting - a wager on a specific segment of the match - and it dominates the illegal betting on cricket, accounting for more than 90 per cent of all wagers.
There are few takers for betting on match results nowadays.
"Nobody wants to wait for five days to get the result of a Test match," says Ramesh Sharma, a long-time punter. "This is a lot more exciting. You can bet on every 15-over session in a Test match or one-day international. In Twenty20, it is a 10-over session."
The introduction of T20, as many critics warned, has boosted the illegal betting business. Punters like it because results are available quickly and, as multiple games are often played on the same day, it is a big money-spinner.
"There is more focus on the shorter version of the game mainly because punters are comfortable and the suspense is over the same day, and in the case of T20 within four hours," Kiranbhai says.
Bookmakers in Mumbai fall into three general categories, based on to the size of wagers they can handle.
The lowest in the hierarchy, who rarely accept wagers of more than Rs25,000, operate from anywhere that is convenient - from cars parked on the roadside, a mall cigarette shop or while having tea at a restaurant.
In the middle are operations like Kiranbhai's, which accept bets of up to Rs2 million and are run out of offices, shops or rented homes. They prefer to do their business over the telephone; the coming and going of punters would attract too much attention.
Then there are the bookmakers who have no limit on the amount that can be bet. They sometimes operate from rooms at five-star hotels, but like all bookmakers, they are fluid in their movements. There are no fixed bases and they often shift locations to avoid detection.
Bookmakers in the top bracket are the ones who decide the odds, and the rest of the crowd follows them. The smaller networks check in by phone and adjust their odds accordingly, although the advent of online gambling has provided smaller bookmakers with another source of odds for some wagers.
"[There are] four or five whose odds are widely circulated between the network of bookies, both big and small, and often are the benchmark for all betting that takes place," Kiranbhai says. "These bookies have highly skilled men, who rely on the odds of probability and consider the venue, the weather, the history of the ground, the individual strength of the competing teams before opening the ante-post [before the toss] odds."
Once a match starts, new odds are set, usually after the first over in an ODI or after the first two balls of the first innings in a T20 match. The odds change after every wicket and high-scoring over, and sometimes more frequently.
"Simply put, the odds change with every ball and the target, too, changes accordingly," Kiranbhai says. "More of this is plain guesswork, but mind you bookmakers rely on the instinct of the specialists employed by them."
It is widely believed that many of the men who set the odds are involved in spot-fixing.
One such case is currently being investigated by Scotland Yard in England. Mazhar Majeed was filmed in a sting operation by the News of the World newspaper and is under police scrutiny as inquiries into alleged spot-fixing continue.
"I don't want to get involved in all these things," says Rahim Khan, a Mumbai businessman. "I often used to bet close to Rs8m in a single day, but I have stopped. I know enough now and prefer to stay away. And those three cricketers [the Pakistan players implicated in the scandal] are not just the only ones."
Like many cricket gamblers, Khan is convinced that corruption is rife across the sport.
"Virtually every game is fixed in some way," he says. "The no-balls and wides, which seem normal; the dismissals in the 90s, which would seem like bad luck; the surprising declarations or bowling changes. And it is not just one team, Pakistan. Every team is involved, but unlike Pakistan, they may do one game in five or six. If you know the right people, you can make a killing on every session."
Sharma vouches for that. He claims to have been burned by at least one fixed match. "It was a Test match between the West Indies and Pakistan, with the West Indies needing some 30 runs with their last-wicket pair at the crease," he says. "There was no way Pakistan could lose that Test from there, so I put Rs12m on Pakistan. But they incredibly lost."
Most matches involving Pakistan are looked at suspiciously in the Indian betting markets. For a long time the bookmakers refused to take bets on Pakistan's matches, especially after betting on matches was declared "null and void" by the bhais (underworld dons) following suspicions of match-fixing.
Sharma said he refused to pay up on his Pakistan bet and appealed to the bookmakers. His connections allowed him to escape without paying, but not all punters are as lucky. They have to pay up, or face the consequences.
"Trust is the most important factor between bookies and punters," Kiranbhai says.
At the highest level, it can be a dangerous game. A few men have been killed as a result of gambling and match-fixing, the most prominent being Ashraf Patel, a diamond merchant who was shot dead in November 2000. Police confirmed match-fixing as a motive in his murder, saying he was the target of a "powerful bookie network that stretches from Mumbai to Dubai".
Ibrahim, the alleged leader of the Mumbai syndicate, moved in Dubai in 1984 and allegedly operated his empire from there. He was often seen at cricket matches in Sharjah, but he fled the UAE after being named as a suspect in the Mumbai explosions of 1993.
Wanted by Interpol and labelled a "Specially Designated Global Terrorist" by the US Treasury Department, he reportedly runs his operations from Pakistan now.
The bookmakers deal strictly in cash. Gamblers who owe money, particularly those in other countries, often pay through hawala - illegal money transfer channels. They give the money to an agent, whose associates in India deliver cash to the bookmaker within hours.
For local wagers, punters often make the payments or receive their winnings in person. The bookmaker sometimes goes around a neighbourhood settling his accounts.
Kiranbhai does not accept allegations that all matches, or different segments in a match, are fixed. He does accept, however, that some bookmakers at times profit greatly by knowing in advance how a certain player will perform.
"We call it player fixing and it is very rare," he says. "Bookmakers in the know generally lay bets with other bookmakers and make a huge killing.
"Sometimes, their businessmen friends will make huge bets on their behalf, or on behalf of players as well, based on this prior information.
"But it is very rare. If the bookmaker accepting the bets gets suspicious, he will cancel them and the word will spread in the market. So it is not as easy as people think. We generally base our odds on probability and expert opinions, not prior information."
Bookmaking can be a lucrative business, but it is also a risky one. Scores of bookmakers have gone bust and dozens are rumoured to have committed suicide.
Many have been victims of match-fixing themselves.
"Recently one of the bookmakers refused to pay up because he believed a certain match was fixed," Kiranbhai says.
"He started receiving threats and, fearing for his life, he escaped to South Africa. But they got him even there - his body was found chopped into pieces.
"So most of us would prefer matches to be honest. We risk as much as the punters when the matches are fixed."