A badly injured Anbuselvan (Suriya) is lying on the bank of a stream, thinking about his wife Maya and how he needs to rescue her. The story moves quickly from this opening scene to a flashback of Anbuselvan’s time as a young policeman.
Anbuselvan was an honest, daring IPS officer with the Chennai police as the Assistant Commissioner of Police (ACP) in the Crime Branch. As he has no relations in life, he lived with no fear. Anbuselvan and his friends, Shrikanth (Daniel Balaji), Arul (Vivek Anand) and Ilamaran (Rajan), have been recruited for part of a special unit of police officers who are battling organized crime in Chennai. Violent and laconic, Anbuselvan finds little patience for a personal life. The unit is ruthless in its confrontation with criminals, going as far as assassinating gang members; the unit is finally disbanded by human rights authorities; Anbuselvan is posted to Control Room Duties.
One day a school teacher named Maya (Jyothika) rebuffs Anbuselvan's routine questions regarding safety, not knowing that he is a police officer. He meets her again when she and her friend are questioned for driving without a license. However, Anbuselvan lets them off with a warning. When one of Maya’s students has a problem with local kids, she asks Anbuselvan for help. Anbuselvan resolves this problem, a mutual respect grows between them and they begin seeing one another. When Maya gets into a road accident, Anbuselvan helps her to recover and they fall in love. Shrikanth and his wife, Swathi (Devadarshini), become good friends with Maya.
In response to rising levels of crime in the city, when the son of an influential movie producer is kidnapped and killed, the special unit is reassembled by commissioner with all four back in the crime branch. The unit tracks down and kills the head of the gang that was responsible. The brother of the gang leader, Pandiya (played by Jeevan), returns from Mumbai and takes over the gang, promising revenge over his brother’s death. Pandiya and his gang members target the families of the men in the special unit, but the police close in and a badly injured Pandiya barely escapes Anbuselvan.
Maya and Anbuselvan get married and leave for Pondicherry. But the next day, Pandiya and his thugs enter the cottage the honeymoon couple are staying in and attack Anbuselvan, leaving him for dead, and kidnapping Maya. This brings the viewer back to the opening scene of the movie, in which Anbuselvan is battling for life, but thinking only about rescuing Maya.
Shrikanth and Arul arrive at the cottage, discover Anbuselvan and take him to the Pondicherry Government Hospital. Shrikanth reveals that his wife Swathi was kidnapped earlier and confesses that it was he who gave away Anbuselvan’s location to Pandiya, for the safe return of Swathi. Shrikanth feels extreme remorse over what has happened. Whilst in the hospital, they receive a message from Pandiya to meet him at a particular location. When they go there, they find a package containing the severed head of Swathi. Shrikanth is distraught at seeing his wife's head and in an agony of grief and guilt at being responsible, he commits suicide by shooting himself. Anbuselvan tracks down Pandiya before he can escape from Tamil Nadu and fights with the gang. Pandiya stabs Maya to distract her husband and she dies in Anbuselvan’s arms. An enraged Anbuselvan tracks down Pandiya and, in a final encounter, kills him.
An epilogue shows that Anbuselvan, after the death of Maya, continued his job as an IPS officer some weeks later. An alternative ending was shot and placed in the DVD version with a running commentary by Gautham Menon, in which Maya comes alive and he explains why this ending was not used in the version for cinema release.Suriya as Anbuselvan
Jyothika as Maya
Jeevan as Pandiya
Daniel Balaji as Shrikanth
Devadarshini as Swathi
Yog Japee as Sethu
Vivek Anand as Arul
Rajan as Ilamaran
Rajeevan as Maya's brother-in-law
Gautham Menon as Vasudevan Nair
Birla Bose as Assistant commissioner
Cool Suresh as Rogue
Ramya Krishnan in a special appearance for "Thoodhu Varumaa" song
R. D. Rajasekhar in a special appearance for "Oru Ooril" song
The film was initially titled as Paathi (Half), before the team opted to change the title to Kaakha Kaakha. Menon revealed that he was inspired to make the film after reading of articles on how encounter specialists shoot gangsters and how their families get threatening calls in return, and initially approached Ajith Kumar, Vijay and Vikram for the role without success. The lead actress Jyothika asked Menon to consider Suriya for the role, and he was subsequently selected after Menon saw his portrayal in Nandha. He did a rehearsal of the script with the actors, a costume trial with Jyothika and then enrolled Suriya in a commando training school before beginning production, which he described as a "very planned shoot".
The film consequently opened to high positive reviews from critics on the way to becoming another success for Menon, with critics labeling it as a "career high film". Furthermore, the film was described as for "action lovers who believe in logical storylines and deft treatment" with Menon being praised for his linear narrative screenplay.
Gautham Menon subsequently remade the film in Telugu for producer Venkata Raju and went on to claim that the new version was better than the previous version. In Gharshana (2004), Venkatesh portrayed Suriya's role while Asin portrayed Jyothika's role. In July 2004, Menon also agreed terms to direct and produce another version of Kaakha Kaakha in Hindi with Sunny Deol in the lead role and revealed that the script was written five years ago with Deol in mind, but the film eventually failed to take off. Producer Vipul Shah approached him to direct the Hindi version of the film in 2010 as Force with John Abraham and Genelia D'Souza, and Menon initially agreed before pulling out again. The film was also made in Kannada in 2011 as Dandam Dashagunam with Chiranjeevi Sarja and Divya Spandana in the title roles. Menon and the original producer, Dhanu, also floated an idea of an English version with a Chechnyan backdrop, though talks with a potential collaboration with Ashok Amritraj collapsed. The storyline of the movie was used in the Oriya movie ACP Ranveer.
In addition to the following list of awards and nominations, prominent Indian film websites named Kaakha Kaakha one of the 10 best Tamil films of 2003, with Rediff, Sify and Behindwoods all doing so. The film was, before release, in "most awaited" lists from film websites.
The film's music was composed by Harris Jayaraj, who reunited with Menon after the successful soundtrack of Minnale. All lyrics written by Thamarai.Upon release,the soundtrack received acclaim from critics and became the most commercially successful soundtrack of 2003. Due to its popularity, Harris Jayaraj earned his second Filmfare Award for Best Music Director and his first Tamil Nadu State Film Award for Best Music Director and ITFA Award for Best Music Director.