In the game of blackjack, an ace--which equals 11--added to a face card--which equals 10--produces the desired winning hand of 21. In 21 the movie, the sum of its cinematic parts doesn’t exactly equal a win.

Bringing Down the House: The Inside Story of Six M.I.T. Students Who Took Vegas for Millions first detailed the exploits of card-counting M.I.T. students run amuck in Las Vegas in book form. The screen adaptation strays from its source material by choosing to focus on a single narrative and (of course) hyping up the drama. Nerdy, sheltered genius Ben Campbell (Jim Sturgess) wants simply to finish up a successful scholastic run at M.I.T. and begin his pursuit of a medical degree at Harvard. Only problem is he doesn’t have the dough to live the dream. Recognized by his math professor Micky Rosa (Kevin Spacey) as quantitatively gifted, dear Ben is recruited to join an elite underground club of undergrads who spend their weekdays in classrooms and weekends cavorting and cashing in at Las Vegas casinos. Their success at the tables lies in their ability to count cards while playing blackjack. Decadence and deceit come with a price, though, and like Alice falling into Wonderland’s rabbit hole, Ben doesn’t come out of this adventure unscathed.

The true tale that inspired 21 can hook any audience member into a viewing, but what transpires on-screen is categorically less entertaining. The actors are serviceable: Sturgess is an okay mix of charm and confusion, but as a solo act can’t hold the picture up. It is only when the group dynamic is on that the players work best. Spacey is consistent but nothing special as the two-faced teacher who is a sage tutor one moment and turncoat the next. It is in the unfolding of the plot, however, where 21 really gets stagnant. Perhaps there is a limited amount of excitement that can be extracted from watching people sitting in casino pits playing cards.

The single-disc DVD's (Sony Pictures Home Entertainment, MSRP: $28.96) extras are limited to a single audio commentary and three short featurettes.

During the filmmaker commentary, director Robert Luketic and producers Dana Brunetti and Michael De Luca provide insight on the filmmaking process. Their thoughts are hardly engaging; the comments reflect mostly on the differences between the real-life story 21 is based on and the made-for-screen one.

The first featurette, “21: The Advantage Player,” has the five attractive main actors portraying the M.I.T. students--Sturgess, Kate Bosworth, Aaron Yoo, Liza Lapira and Jacob Pitts--give a short lesson on blackjack. The featurette begins with a history of the game (who knew it had French origins?) and culminates with a how-to on card counting.

“Basic Strategy: A Complete Film Journal” is strictly behind-the-scenes fare. Less comprehensive than it wishes, this look at the film’s journey starts out by discussing the story behind the story: how Bringing Down the House author Ben Mezrich met the intrepid M.I.T. student-run blackjack team, translated their story into a nonfiction work and later hooked up with producers interested in making the book into a movie. One anecdote in the featurette reveals that when the producers were shopping around the script, the only studio interested in it was MGM--the MGM casino being one of the spots the real M.I.T. students frequently hit in their card counting encounters. From here the featurette delves into the different characters, as well as the background on the actors chosen to play them. It shows how the actors learned casino protocol, gives a brief look at the Genesis digital camera used to shoot the production and, finally, shows the experience of filming in a real, fully operational casino.

The last featurette, “Money Plays: A Tour of the Good Life,” is led by 21’s production designers who chat about the mass differences between the movie’s two major locations: Boston, Massachusetts and Las Vegas, Nevada. From the esteemed halls of East Coast-based academia to the ostentatious vivacity of a very sinful city, the designers set out to establish a clear juxtaposition between the safe haven Ben was familiar with and the new, alluring domain he became entangled in. The production team also talks about what one assumes was very difficult: tedious research into the high-roller lifestyle.

A two-disc deluxe edition of 21 (MSRP: $34.95) is also available, but the only extra feature buyers are really getting is a bonus digital copy of the film, which is hardly worth the extra $5.99.

21 has a great concept. Unfortunately for viewers, it has a less enticing interpretation.

21 is now available on DVD.