Roy Kapoor(Abhishek Bachchan) is a conman. He is not ashamed of it, in fact he believes himself to be "Bluffmaster". Roy's girlfriend Simi(Priyanka Chopra) is ignorant about his truth as he has conned her too into believing that he is an investment banker. One day he cons a film producer(Tinu Anand) out of his money. Unfortunately, the producer turns out to be an acquaintance of Simi & Roy's true face is exposed to Simi. Simi calls their wedding off.
Some weeks past this episode, Roy sees an amateur conman Dittu(Ritesh Deshmukh) conning a doctor called Dr.Bhalerao(Boman Irani). Roy meets & foils Dittu's plans a couple of times, upon which Dittu pesters Roy to become his mentor. Roy reluctantly accepts Dittu(who is a film buff as well), but now he wants to make amends with Simi.
One day, Roy starts experiencing blurring of eyes, unbearable headache & blackouts. Dr.Bhalerao checks him & tells that Roy has brain tumour & 3 months to live. Roy is shattered, even more as Simi is not ready to accept him. When Roy gets signs that Simi is engaged to someone else, Roy resigns to his fate & turns his attention to Dittu.
Dittu reveals that his father was a simple man who was conned of his life savings by a share market scam, apparently pulled by Chandru(Nana Patekar). Chandru is a whimsical but ruthless man. Roy decides to do use his skills for Dittu. When Roy sees a news footage about a robbery in a jewellery shop, Roy gets an idea to con Chandru.
Roy sends one of his men as police to Chandru to give him a list of serial numbers of all the notes stolen in the "heist"(which they have themselves printed). Then Roy & Dittu turn themselves up at Chandru's hotel as suspicious characters with lots of money. When Chandru is convinced that they are the thieves, he proposes to give them any amount for the stolen loot. They strike a deal with Chandru.
Meanwhile, Simi re-enters Roy's life after learning that he was telling the truth. She has broken her marriage & wants to be with Roy in his last days. She learns from Roy why he took up to being a conman. Meanwhile, Chandru promises Roy the full share if he eliminates Dittu. Roy cons Chandru to believe that he has killed Dittu. Chandru promises him his money next day.
Next day, the deal takes place in a theatre, where Dittu suddenly shows up & kills Roy. He elicits Rs.5 crore from a frightened Chandru. Chandru leaves, after which it is revealed that Roy & Dittu have successfully conned him. Unfortunately, Omar, a man whom Roy had conned earlier sees this & figures out the whole truth.
He confronts the duo & scoots off with the money. Roy faces one more blackout & opens his eyes in Dr.Bhalerao's hospital. He sees a pained look on Dittu's face who has learnt Roy's secret. Dr.Bhalerao tells Roy that his cure is possible in foreign, but money is the problem.
Roy withdraws all his life savings. Suddenly, he gets a call from Simi. He answers, but hears the voice of Chandru. Chandru tells him that he has kidnapped Simi & knows the whole story. Roy promises to give him his money back if he does not harm Simi. Roy heads towards the rendezvous location with Dittu, telling him to take Simi to a safe place the moment she comes down. Roy comes on the top floor to meet an angry Chandru.
Chandru leaves Simi, but has a scuffle with Roy. He angrily pushes Roy from the roof. Roy falls down, but instead of dying, ends up on an inflated plastic bed & survives. Confused, he turns towards people surrounding him, only to learn that they thought it was a film shoot. Roy tries to call everyone from Simi to Chandru, but gets no response. Then he realizes that he has been elaborately conned.
After learning that he has no brain tumour, he heads to a place where he thinks everybody would be present. As expected, he meets everybody & as Dittu gives real introduction of every partner, Roy is left amazed. Dr.Bhalerao is actually a vet while Chandru is the script writer for all the drama(who in reality is afraid of smallest of the things). Roy learns that Dittu is the son of the producer he had conned & that even Simi's second engagement was fake.
Then, Dittu explains in detail how the whole operation was planned. After learning that it was Simi & Dittu's idea to teach him a lesson, Roy approaches & makes up with Simi.