Manickam runs a lottery shop in Kumily, near the Tamil Nadu – Kerala border. His wife Ananya is in debt due to the pressure of running the family. One of their two school going daughters, is speech impaired and lakhs of money is required for her treatment which is beyond their means. In this situation an impoverished old man with his own family problems buys a lottery ticket from Manickam but cannot pay for it as he had lost his money. The old man requests Manickam to keep the lottery ticket promising to come back and pay for it. As luck would have it the ticket that Bharathiraja picked wins the hefty sum of One and a half crores. Manickam’s wife and family members ask him to cash in on the lottery ticket that will solve all their problems. What decision the morally upright Manickam takes and what problems he faces because of that is what ‘Thirumanickam’ is all about.