The movie portrays the life of an old farmer in a small village in Tamil Nadu over the period of a month. Mayandi is an 80+ year old farmer, living a frugal lifestyle. He talks very little and displays very little emotion. He is tasked with providing the symbolic first grain for the village temple's annual ceremony as there is no other farmer in the village. The rest have sold their lands to financiers for supposed developmental projects. Mayandi plants a new batch of paddy in his field, and one day, he finds a peacock and 2 peahens dead in his field. He considers them vehicles of his favorite God Murugan and buries them in his field. A fellow villager sees him bury the birds. Soon, Mayandi is arrested for the crime of killing a peacock (because it is India's national bird). It is then revealed that some years ago peafowl were killed in the village and the investigating police were heckled and there were no witnesses. The police wishing to avenge their humiliation find a witness and file a case against Mayandi, who is taken into judicial remand. He is then brought to court where he states to the magistrate (Raichal Rebecca) the facts and explains that the witness only saw Mayandi bury the birds, not the act of killing them. She reprimands the police for filing a false case and orders them to submit a changed report. However, since the FIR had been filed and filing a new report takes time, Mayandi is ordered to spend 15 days in jail. Mayandi mentions his newly-planted crop that needs regular watering and the magistrate orders the police constable to take care of that.

The police delay filing the changed report and neglect the care of the field while Mayandi's stay in prison gets extended. Mayandi's relatives in the village take pity on the police constable (who is watering the field) and agree to take up that task themselves. When pests attack the crop, Mayandi advises them on how to control them with a traditional spray, but this is laborious and Mayandi's relative buys a pesticide that is pushed by the village agro-chemical dealer. Mayandi makes an escape while waiting for his hearing and discovers the crop destroyed. The magistrate finds him in the field and tries to hasten a speedy release, while also ensuring support for a new crop to be planted and raised in time for the festival. The festival itself involves Ayyanar deities (including Karuppu Sami), propitiated by a coming together of all the caste groups in the society, including the village potter who has nearly lost his livelihood.

The movie ends happily after it nearly seems to end tragically.

There are two side stories. One is that of a village simpleton Ramaiah, played by Vijay Sethupathi (the producer) who has gone insane following the death of his love. In several places, it is hinted that he is the sane one in a world gone mad. Another is that of Yogi Babu and his elephant, bought after selling off his land to a financial institution. There are also commentaries on hybrid seeds, industrial animal feed, and other high-input practices that are destroying sustenance farmers.