Kanmashi movie tells the story of a young girl Sethulekshmi (Nithya DAs) who is fondly called 'Kanmashi' by all. She and her gang of little kids spend their time fooling around and getting rid of all the marriage proposals that come for heri. When Vishnu (Vineeth KUmar) who is a young textile designer comes to work in the textile mill owned by Padmanabhan Menon (Nedumudi Venu), things take a different turn.
Kanmashi, who has been avoiding marriage and even mischievously fooling Murugan (Kalabhavan Mani), her maternal cousin who is madly in love with her, falls in love with Vishnu. Vishnu too falls for 'Kanmashi'. But Vishnu has a definite purpose for coming to the place. And when the elders arrange the marriage between Vishnu and Varsha, Padmanabha Menon's granddaughter, matters become worse.