"21" is the fact-based story about six MIT students who were trained to become experts in card counting and subsequently took Vegas casinos for millions in winnings.
Ben Campbell is a young, highly intelligent, student at M.I.T. in Boston who strives to succeed. Wanting a scholarship to transfer to Harvard School of Medicine with the desire to become a doctor, Ben learns that he cannot afford the $300,000 for the four to five years of schooling as he comes from a poor, working-class background. But one evening, Ben is introduced by his unorthodox math professor Micky Rosa into a small but secretive club of five. Students Jill, Choi, Kianna, and Fisher, who are being trained by Professor Rosa of the skill of card counting at blackjack. Intrigued by the desire to make money, Ben joins his new friends on secret weekend trips to Las Vegas where, using their skills of code talk and hand signals, they have Ben make hundreds of thousands of dollars in winning blackjack at casino after casino. Ben only wants to make enough money for the tuition to Harvard and then back out. But as fellow card counter, Jill Taylor, predicts, Ben becomes corrupted by greed and his arrogance at winning which lets his feelings get in the way, and it also puts Professor Rosa, as well as the group, on the radar of a brutal casino security enforcer, named Cole Williams, who holds a personal grudge of some kind against Rosa which threatens to undo everything the students have learned and earned.
Ben Campbells dream has always been to go to Harvard Medical School. He is well on his way - hes bright and hard working, which he applies to both his school work and his part-time but low paying job at a mens clothier. In his senior year at M.I.T., he has been accepted to Harvard Medical School, but does not have the $300,000 it will take to finance it. He impresses one of his professors, Mickey Rosa, in class with his quick mind and ability to deal with the issue at hand without letting his emotions take over. Based on that, Mickey invites him into his small but secret society of students that have a system of winning at black jack through counting cards. They play in Vegas on a system of codes, rules and alternate identities, and where each person involved has a very specific role. This offer does not initially interest the straight-laced Ben until he is approached by Jill Taylor, another of those in the group and upon who Ben has a crush. He accepts their offer to be one of the big players on the understanding that he will do it only until he has enough to finance his Harvard education. Once Ben gets a taste of the big life, it starts to affect his original plan, including having unforeseen consequences of alienating his closest friends. He is also unaware that a casino security consultant named Cole Williams is on their tail, Williams who is working on his own personal agenda. Ultimately, greed, pride, ego, desperation and revenge all play a role in how involvement in this group affects Bens life plan.