Ben Campbell (Jim Sturgess) is a bright and somewhat clumsy student with a very promising future, but with financial problems that may hinder his entry into Harvard Medical School . He is accepted, but he cannot afford the $ 300,000 entry fee. Ben faces stiff competition for the prestigious Robinson Scholarship, which would have borne the full costs of medical school. The director informs him that the scholarship would go to the student who would be able to “enlighten” him more telling him the most fascinating life experience.
So Ben begins to tell him his story: when he was a student at the Massachussetts Institute of Technology in Boston , thanks to his talent for numbers and calculations he is noticed professor Mickey Rosa (Kevin Spacey), a former “counter” .
After submitting to him the Monty Hall problem, which Ben solves, and seeing his score in the latest nonlinear equation exam, where he got 97%, Rosa invites Ben to join the Blackjack team , a group of students with outstanding mathematical skills consisting of Choi, Fisher, Jill and Kianna.
The tactic , explained to Ben da Rosa, who acts as his mentor, is always the same: everyone enters the casino separately pretending not to know each other, and is divided into two groups: the “explorers” always play at a minimum and keep track of the cards, then sending signals to the “pointers” whenever the pot becomes interesting. The money for the game is provided Rosa. The extraordinary performances of Ben, who already on the first night earn more than Fisher, the previous spearhead of the group, attract the attention of Jill, who begins to have sincere feelings towards him, obviously paid.
All this, however, makes Fisher jealous, who exaggerates one night: heavily drunk, he sits at the table where Ben and Kianna (who obviously were in the black) were playing, which is absolutely against the rules, and starts to repeatedly insult Ben. Although Ben tries to ignore him, it continues until Fisher hits the glass of a woman sitting next to him, wetting her, and his companion, a disreputable subject, starts a fight even pulling out a gun and shooting some shots, which fortunately all end up on the ceiling.
The group reunites at a nearnightclub, and Fisher is brutally kicked out of the team an enraged Rosa. Ben also finds a clever ploy to swap the chips before the casino changes them all (common practice after a fight), having the dancers swap them out.
However, all these winnings and this bustle caught the attention of Cole Williams , an expert in charge of safety who got to know Rosa years ago. Meanwhile, Ben finally conquers Jill, and the two copulate in a suite.
Distracted his commitments in Vegas, money and love, Ben ends up neglecting his old friends, with whom he was carrying out a major engineering project, thus being dumped as both a friend and a collaborator on the project. Deeply saddened, Ben does not have the concentration necessary to face another weekend in Las Vegas , and begins to lose, persistently continuing to play without counting, but relying only on luck. This will lead him to lose $ 200,000, obviously from Rosa, who will get mad and leave the group to himself returning to Boston alone, not without first warning Ben that one way or another he will get his money back.
At first lost, the group is reassembled Ben, who will convince them that Rosa was useless, that she kept 50% of the profits without playing and that they can do without him. The only one who is against it is Jill, who reminds Ben of her own words, which is that she would have lived that life just to raise the $ 300,000 needed the university, while Ben, his own admission, has already made 315,000.
They then head back to the casino and come back to win, but Rosa, disguised and hidden behind some slot machines, tips Williams. As soon as the group sees him he vanishes, except for Ben who is taken, taken to a basement and beaten (which happened to all those discovered Williams to count). Fortunately, back in Boston, Ben finds his room upside down: Rosa has turned it upside down, discovered his hiding place and cleaned it. As if that were not enough, he has no evidence against Rosa and is no longer his favorite, so his grades start to drop too.
Apparently Ben has lost everything: his team, his money and his future at medical school. Having understood his mistakes, he recovers his old friends (who in the meantime have won the first prize thanks to the engineering project) telling him everything; and Jill, who will support him in his plan to get revenge on Rosa.
This is how he introduces himself to Rosa’s house during an important party full of wealthy people, and convinces him to return to Las Vegas for one last time. New facial recognition software is flooding the market and stealing jobs from people like Williams, who is being fired casinos. This software is so sophisticated that it will be impossible to enter a casino without getting caught, so time is running out. The group will have to go to one of the few casinos that does not yet have this technology, and given the need to make a lot of money in a short time, an experienced player (even if withdrawn) like Rosa will have to participate not only as a lender but also as a player. The professor agrees, and once they get to the casino he and Ben immediately start betting big and winning big money. However, they are discovered Williams, so Ben puts all the chips he can grab into a bag and begins a long escape with Jill and Rosa through the kitchens and warehouses of the casino. After having the chips delivered, Rosa separates from the group with the warning to rejoin the night: no one should leave the city alone.