A Lucknow based lawyer, Jagdishwar Mishra, better known as Jolly (Akshay Kumar) works as an assistant to Rizvi Sahab who is Lucknow’s famous lawyer. Jolly belongs to Kanpur and comes to Lucknow to become a big lawyer and own his personal chamber.
In order to arrange money for his own chamber, Jolly lies to a pregnant lady, Hina (Sayani Gupta) and convinces her to give him rupees 2 Lakh as fees so that Rizvi Sahab would fight her case. Jolly uses that money to pay the final payment for his own chamber and opens it with a ceremony. When Hina finds out that she has been bluffed by Jolly, she commits suicide. Everyone blames Jolly for her death, including Jolly's father, who worked for 30 years as a clerk for Rizvi Sahab.
Filled with guilt, Jolly along with his wife Pushpa (Huma Qureshi) & fellow lawyer Birbal (Rajiv Gupta), decides to fight Hina's case & files a PIL. He soon discovers that Hina's husband Iqbal Qasim (Manav Kaul) was killed in a fake encounter by Inspector Suryaveer Singh (Kumud Mishra) on the very next day of their marriage in order to get a promotion. Singh also shot a fellow constable, Bhadouriya, in his thigh, in order to show the encounter genuine. Bhadouriya later died due to excessive bleeding, Inspector Suryaveer Singh then hires the best lawyer in Lucknow Pramod Mathur (Annu Kapoor), his friend, to fight his case.
On the very first date, Jolly requests the court for an impartial enquiry into the encounter once again. However court gets adjourned. Jolly is able to get FIR copy & papers regarding the case with the help of a bookie Guru Ji (Sanjay Mishra) in Varanasi by paying him Rs. 5 lakhs. Later he is able to track Ram Kumar Bhadouriya, the son of the constable who died in the fake encounter However, during the court hearing, under a heated argument, Jolly slaps advocate Mathur. Court orders a narco test of Ram Kumar. Jolly is attacked by two henchmen sent by Inspector Singh, but survives with two bullet wounds. However, Singh is suspended from Police Department.
Advocate Mathur, uses his power and money to tamper with the narco test video of the witness and proves Jolly wrong in the court. Judge orders the temporary suspension of Jolly's license as a lawyer, but later, Chairman of Discipline Commitee, Rizvi Sahab gives Jolly, 4 days of time to prove himself correct. Jolly soon notices that a Kashmir police constable visited Lucknow to identify the terrorist during Iqbal and Hina's wedding. Jolly travels to Kashmir and meets the constable, Fahim Butt, who is now suspended and arrested in a fake case. The constable reveals that the person who died in the encounter was not the real terrorist and is ready to give the statement in the court. Jolly manages to bring the constable to Lucknow court in the next hearing to prove that Iqbal Qasim was not the real terrorist. Meanwhile, Jolly also convinces the police commissioner to tell the truth or else, he will file PIL against all the encounters done by him.
Advocate Mathur, tries his best to avoid constable from giving statement in the court as he creates tussle in the courtroom by insulting the judge. The court hearing proceeds till midnight, but the Judge still decides to carry on. After constable's statement Jolly surprises everyone by bringing a Hindu Brahmin Pandit in the court (with the help of police commissioner), & claims that he is the real terrorist and has been arrested by the police in Mathura. Jolly cross questions the pandit in the court by asking him deep details of Hindu Vedas. The pandit finally breaks up and admits that he is the terrorist, Mohammad Iqbal Quadri, for whom police were searching and he had bribed Inspector Singh to set him free, hence police had encountered Iqbal Qasim to close the case.
Judge then declares Iqbal Qasim innocent and orders the arrest of the terrorist, bails Ram Kumar, son of the constable and gives life imprisonment to Suryaveer Singh along with his accomplices for charge of murder, erasing evidence, misguiding court and showing fake evidences and that’s how Jolly finally finds the real convict and solves the case. The film concludes with Jolly winning everyone’s heart and goes out of the court with lots of praises from not only the public but also Rizvi sahib.