21 is a 2008 American heist drama film directed by Robert Luketic and starring Jim Sturgess, Kevin Spacey, Laurence Fishburne, Kate Bosworth, Liza Lapira, Jacob Pitts, Aaron Yoo, and Kieu Chinh. The film is inspired by the true story of the MIT Blackjack Team as told in Bringing Down the House, the best-selling 2003 book by Ben Mezrich. Despite its largely mixed reviews and controversy over the film's casting choices, 21 was a box office success, and was the number one film in the United States and Canada during its first and second weekends of release.

DETAILED PLOT

Ben, a mathematics major at the Massachusetts Institute of Technology, is accepted into Harvard Medical School but cannot afford the $300,000 tuition. He applies for the prestigious Robinson Scholarship which would cover the entire cost. Despite having a Medical College Admission Test score of 44 and high grades, he faces fierce competition, and is told by the director that the scholarship will only go to whichever student dazzles him.

Back at MIT, a professor, Micky Rosa challenges Ben with the Monty Hall Problem which he solves. After looking at Ben's 97% score on his latest non-linear equations test, Micky invites Ben to join the MIT Blackjack Team, consisting of fellow students Choi, Fisher, Jill and Kianna. Using card counting and covert signalling, they increase their probability of winning at casinos, leading them to earn substantial profits.

Over many weekends, the team is flown to Las Vegas Valley and Ben comes to enjoy his luxurious life as a high roller big player. The team is impressed by Ben's skill but Fisher becomes jealous and fights him while drunk, leading Micky to expel him. The head of security, Cole Williams, has been monitoring the team and begins to focus on Ben.

Ben's devotion to blackjack causes him to neglect his role in an engineering competition, which estranges him from his friends. During the next trip to Las Vegas, he is emotionally distracted and fails to walk away from the table when signaled, causing him to lose $200,000. Micky is angered and quits the team, demanding Ben repay $200,000. Ben and three of the students decide that they will continue to play blackjack without Micky but they are caught by Williams, who Micky tipped off. Williams beats up Ben and warns him not to return. He also reveals his own personal history with Micky Rosa, once a successful card counter who got Williams fired after winning over a million dollars in one night at his casino while he was away at his father's funeral.

Ben learns he is ineligible for graduation because his course taught by an associate of Micky's is marked as incomplete (with Micky's influence, the professor initially gives Ben a passing grade throughout the year without him having to work or even show up to class). His winnings are stolen from his dormitory room. Suspecting Micky, Ben confers with the other blackjack students and they persuade Micky to make a final trip to Vegas before the casinos install biometric software. The team puts on disguises and returns to Planet Hollywood, winning $640,000 before Williams spots them.

Micky flees with the bag of chips, jumping into a limousine but realizes it was a setup when he discovers that the chips are fake. It is revealed that Ben and Williams made a deal to lure Micky to Las Vegas so that Williams may capture him. Williams' men take Micky and Cole explains he's going get in contact with a friend of his with the IRS about Micky's untaxed winnings. In exchange, Williams commits to allowing Ben to keep his winnings for that day, but later double-crosses him as he is leaving, taking the bag of chips at gunpoint. When Ben protests Williams explains he needs retirement funds, whereas intelligent people like Ben will always find a way to succeed.

Ben's long-time friends (with whom he has reconciled) Miles and Cam also turn out to be quite good at card-counting while working with Choi and Kianna during Micky's capture and as such, the 6-person team make a lot of money despite Williams's robbery of Ben and Micky's chips. The film ends with Ben recounting the tale to the dazzled and dumbfounded scholarship director.