Unnikuttan, Dileep, is a simpleton whose life circles around the central jail. He was born and raised there with his father Kesavan, Siddique, and mother Janaki, Vinaya Prasad, before being moved to a child care facility at the age of six. Inside the prison walls, he finds a strange solace, serving as a substitute for the small punishments others face in everyday life. In his late thirties, he remains unmarried, and many people around him urge him to marry for real love and a life beyond the jail’s routines.
Within the confines of the jail, he falls for Radhika, Vedhika, and vows to marry her, hoping to help her resolve the troubles she carries. She was jailed on a drug charge, and she confides in him that she has witnessed a minister commit murder. This truth haunts her, and Unnikuttan works to understand the story behind the wrongful case she endures, because she saw the minister kill a man named Karunan. The danger intensifies as a killer tracks her, and her uncle misleads those who pursue her by claiming she has found work and left for Delhi.
While at her aunt’s home, Radhika watches a TV news segment revealing that in the same case, Simon has also been jailed. She eventually decides to hand over the video clip she shot to prove the truth, but is arrested in a sudden turn of events. On parole, Unnikuttan retrieves the video and presents it to the media, helping to clear Simon’s name. In the wake of these events, Radhika is released and the minister is arrested.
A new police officer arrives at the jail as the jail superintendent, a figure who quickly turns strict toward everyone, including Unnikuttan, because he is believed to be the minister’s ally. The tension escalates when a Hindi assailant is sent to kill Unnikuttan; the would-be killer targets many prisoners, but Unnikuttan fights back and kills him in a moment of retaliation. The superintendent then retaliates with brutal force, delivering a harsh beating to Unnikuttan.
Jailor Gopinath, Renji Panicker, arrives to intervene and protect him, threatening to file a complaint that could expose the superintendent’s actions, with prisoners serving as witnesses. Unnikuttan is returned to his cell, and he resolves that he will not come back to the jail again. In the meantime, the minister and the superintendent send a new killer to finish Radhika, but she defends herself and kills him, though this act lands her in custody.
When Unnikuttan is eventually released again, he finds Radhika already arrested. She reveals the full truth about her crime to him, and the minister and the superintendent humiliate him by claiming she killed a man they had sent to jail, while plotting to kill her themselves. Enraged, Unnikuttan turns on them, stabbing both the minister and the superintendent to death, and returns to the jail.
After all the chaos, Unnikuttan and Radhika marry in the jail, choosing a life together against the odds and within the walls that shaped so much of their story.
