The movie opens with a car bombing, and the figure of Sam 'Ace' Rothstein floating through the air. Like ' The Godfather,' it makes us feel like eavesdroppers in a secret place. It's based on a book by Nicholas Pileggi, who had full access to a man who once ran four casinos for the mob, and whose true story inspires the movie's plot. Martin Scorsese's fascinating new film 'Casino' knows a lot about the Mafia's relationship with Las Vegas.