In 2004, a North Indian woman named 'Psycho' Jothi is prosecuted for the murder of 2 young men, kidnapping and murder of five children. But gets killed by the police while resisting her arrest. 15 years later, a dweller in Ooty named 'Petition' Pethuraj (K. Bhagyaraj) revives the case, indicating that Jothi is not guilty and he covets to pose a defense for her. Venba (Jyothika), Pethuraj's daughter and an inexperienced lawyer, attempts to revive the case amidst antagonists.
When Venba chose to work on the case, society turns against her. She faces immense vituperation and humiliation. The defense, i.e. the prominent lawyer Rajarathnam (Parthiban) is a corrupt man who has no conscience of justice being bought by those who can yield it. He represents the powerful father of one of the murder victims, creates more barriers for Venba. Rajarathnam strives to break her debates in court based on technicality.
In the process, some frightful mysteries come out and tests are pitched at Venba, who crosses numerous boundaries to drill out new data about the case that determines Jyothi wasn’t a serial killer.
How Venba strives to get justice for Sakthijothi aka 'psycho' Jothi by crushing fake allegations against her and amidst the toxic bias of people forms the crux of the story while giving out a very crucial message.