Satyaraj, Captain Raju, an infamous professional killer, carries out the murder of a cement contractor on orders from his business rival, Vincent. Balram, [Mammootty], nicknamed "Karadi Balu," is an honest yet notorious and arrogant police officer who manages to seize Satyaraj within a day. However, before he can interrogate him, another investigating officer takes charge of the case.
Vincent, with the help of Sukumaran as Adv. Jayachandran, manipulates witnesses and the investigating officer, tampering with crucial evidence. The maneuver works for a time, and Satyaraj is acquitted of the murder charge. Yet, because he continues to face several other cases, he remains in custody, not released while those trials proceed.
Balram had previously faced accusations of custodial death tied to a boy he arrested, and this taint follows him. Labeled a murderer by public opinion, his relationship with his lover's daughter becomes a point of strain when her father objects. The mounting stress drives him toward alcohol and a pattern of womanizing as a coping mechanism.
Satyaraj eventually escapes from jail with the aid of the Jail superintendent. Radha, Seema, the sister of the teenage boy who was killed and the case against Balram, seeks justice and joins the legal battle led by Adv. Jayachandran. Adv. Jayachandran convinces Radha that Satyaraj possesses documents that could implicate Balram in her brother's death, swaying her to offer safe shelter to Satyaraj.
In a tense turn, Balram discovers that the woman he has been involved with is pregnant, prompting him to propose marriage. During a routine vehicle search, he uncovers incriminating documents and hands them to his superior, only to learn that the superior officer is corrupt and quietly returns the papers to Vincent and Adv. Jayachandran. Balram had already sent a copy to the Central Bureau of Investigation, which leads to the arrest of the superior officer, Vincent, and Adv. Jayachandran.
Radha later learns from Vincent's son that her brother was killed at Satyaraj's orders, and that the senior officer had tried to shield Vincent by framing Balram. Realizing the truth, she discreetly informs Satyaraj's whereabouts to Balram, who prepares to move in for an arrest. Satyaraj, realizing Balram's plan, takes Radha and her friend hostage and makes a desperate bid to flee. Balram gives chase, and after a brutal confrontation, he kills Satyaraj, leaving the officers to arrest Balram.
