The movie "21" opened this week, but the story behind it is already known by many people.

That's because "21" is based on a book that has been a New York Times bestseller for several years called "Bringing Down the House - The Inside Story of Six M.I.T. Students Who Took Vegas for Millions," by Ben Mezrich. (To take advantage of the movie tie-in, the book's cover and its Web page show the title "21: Bringing Down the House - The Inside Story of Six M.I.T. Students Who Took Vegas for Millions.")

In any case, you get the premise in the title and subtitle, but the story sounds even more intriguing than that. "Bringing Down the House" book details how gambling was a fixture on the M.I.T. campus, and how a group of highly intelligent students joined a secret organization that focused on playing blackjack and card counting.

They used a system that enabled them to win at casinos around the U.S. Eventually they worked their way into Vegas, with the help of some investors who stay in the background.

The movie "21" is getting mixed reviews, partly because some reviewers say it squeezes the story into a standard movie-plot format. But regardless of how "21" the movie does, the book "Bringing Down the House" is still available. (You can read excerpts from the first two chapters here.