Takkar revolves around the lives of three characters ? Ravi Malhotra (Suniel Shetty), Mohini (Sonali Bendre) and Inspector De Costa (Naseeruddin Shah). Ravi is a freelance photographer, in love with Mohini, who works hard to make a living so they can be together. Inspector De Costa is an efficient but corrupt cop who takes advantage of criminals by helping them in return for money and then double crossing them; he pretends to be on the side of the law.
No one is considered strong or wise enough to confront De Costa. De Costa one day notices Ravi and Mohini on the beach, and he immediately falls for her. To keep Ravi away from her, he frames Ravi on the day before his marriage to Mohini by falsely implicating him in a drug deal case in a fake raid. Ravi is sentenced to four years of imprisonment. In prison, Ravi decides to study the law so he can fight injustice. He is helped by hardcore criminals who are in jail because of De Costa and want him dead.
In Ravi?s absence, De Costa befriends Mohini. She begins to like and respect him as though he were a good man. After two years, Ravi is released from jail because of good behavior and on recommendation by the circle inspector on Mohini?s pleas. Soon Ravi and Mohini are married. De Costa learns about Ravi?s release from prison and his marriage. Infuriated, he harasses the couple repeatedly to get close to Mohini. But Mohini never gives in to De Costa?s moves. Ravi soon realizes that it was Inspector De Costa who had framed him on the day before his marriage, and he decides to take revenge. He follows De Costa closely, watching all his activities. Being a photographer, he captures the cop on camera.
The circle inspector is killed by De Costa when both of them rescue a group of school children from terrorists holding them captive in a school. This is noted by Ravi, and he makes it known publicly. Soon an enquiry is arranged by the police (on Ravi?s request), and Ravi plays the prosecution lawyer. He traps De Costa in his own words, making him confess his crime. He also provides evidence for the same.
The helpless De Costa is suspended from service. But Ravi and Mohini know that De Costa will never leave them in peace. So they approach his mistress (Archana Puran Singh) for help; she says that De Costa?s desires can be used against him. They hatch a plan. Ravi leaves the house before Mohini, pretending to go out of the city. De Costa learns of this and immediately goes to the couple?s house, where he is met by a surprise reception. Mohini dances with him, pretends to seduce him and, as they enter the bedroom, she screams, and Ravi breaks in. He beats up De Costa badly, and police arrive and arrest the former cop.
De Costa is now jailed. But enemies are not at bay for him. In prison, he comes across the men whom he has jailed, as they are working in the jail compound. The criminals together attack and kill De Costa.
The film ends with De Costa?s burial, as Ravi sticks a cross with De Costa?s name painted on it on the grave. He then says ?Everything has come to an end for good? and walks away with Mohini, as the others look on.