In the heart of Hollywood, hidden beneath the notorious Viper Room, is a narrow hallway that leads to a room with a poker table where billionaires and celebrities once sat.
This was the secret world of Molly Bloom, a Hollywood "poker madam" who says she lured the rich and famous to her table every week for an underground, high-stakes game of no-limit Texas Hold'em.
"People had, probably, six-figure losses, six-figure wins," Bloom told ABC News' "20/20."
Watch the full story on ABC News' "20/20" TONIGHT at 10 p.m. ET.
Just last month, Bloom pleaded guilty to illegal gambling in hopes of staying out of jail. She was sentenced to probation.
Bloom said she was running errands for a wealthy entrepreneur when she first entered the world 10 years ago. At 27, she said, she was given the responsibility to host the games, organizing the cheese plate and drinks for her boss and his high-rolling poker buddies, including Leonardo DiCaprio and Tobey Maguire.
The former cocktail waitress from Colorado said she was immediately intoxicated by the mixture of glamour, wealth, secrecy, and the cash tips she received from the winners.
After making $3,000 in tips the first night, Bloom said, "I got in my car. I locked my car, and I just was, like, screaming."
Dealer Manny Lopez also said he received tips for dealing the cards.
"I remember making $3,000 a night," Lopez told "20/20."
Since no one took a cut from the pot of winnings, Bloom's Hollywood game was legal. For Bloom, perfecting the game for the A-list players meant studying their poker personalities.
According to Bloom, Matt Damon was nothing like the poker addict in his movie "Rounders."
"He was lovely, modest, down-to-earth, very gracious," Bloom said. "And to further that point, he never came back."
On the other hand, Damon's well-known friend, Ben Affleck, according to Bloom, was a regular at the games. And actor Tobey Maguire, Bloom said, assumed an alter-ego when he put on his poker face.
"I used to call Tobey 'Hannibal Lecter' because he could just talk someone off of a good hand," Bloom said. Requests from ABC News' "20/20" for comments from Damon, Affleck, DiCaprio and Maguire were not immediately returned.
Over the years, Bloom said, Maguire won millions of dollars playing and didn't handle losing well.
"Tobey would put [DiCaprio] in the game in order to attract bigger players," said Bloom.
Bloom said she realized she could satisfy Maguire and the regulars and make more money if she began recruiting new players, also known as "whales."
"[Whales] have a lot of money and limited skill," said Bloom.
If a whale wasn't drawn in by the famous actors who attended the games, Bloom said, baseball player Alex Rodriguez was her ace in the hole.
"A-Rod was a novice player, but there's something that happens to grown men, no matter how successful they are, when a professional athlete comes into the room," Bloom said.
While a representative for Rodriguez denied his involvement in the games in 2011, dealer Lopez said that during games, Rodriguez would ask him about the other players' skills.
"He will always talk to me in Spanish, things about the players, like, 'How is that guy?' or, 'Who is this guy?' 'How does he play?' 'Is he a good player?'" Lopez recalled.
By 2009, Bloom said, her tips of 5 to 10 percent were adding up and her reported income topped $4 million.
But Bloom left the celebrities behind and moved to New York, setting up a table in the Plaza Hotel and inviting Russian billionaires and hedge fund managers.
"This was 2008, you know. The economy was falling apart, spiraling," Bloom said. "And I was hosting a game in New York, and there was $5- to $7 million on the table."
Aside from tips, Bloom also began demanding a cut of every pot and, for the first time, she also crossed a line into organized crime. When she declined two mobsters' demand for a piece of her illicit activity, according to Bloom, she was beaten up by someone they sent to her apartment.
"I was deep. Almost one of my first thoughts after he left was, 'How am I going to fix my face before the next game?'" Bloom said.
Eventually, the FBI raided one of Bloom's games.
"And I wasn't at that game, and that was terrifying," Bloom said. "I logged into my bank accounts and they were all seized, all frozen. So that was a pretty clear indication that I was in big trouble."
Bloom fled to Colorado, where she hid for two years, writing a book titled "Molly's Game," about her journey through the poker world of billionaires and poker, until the FBI finally caught up with her.
After her experience of observing the game of poker, Bloom offered this advice to poker players: "Know when to fold. Pay attention to the signs. They're there."
Tune in to ABC News' "20/20" TONIGHT at 10 p.m. ET.
Inside the Life of a Celebrity 'Poker Madam'