We are living in a time where the number of honour killing and related crimes are witnessing an alarming rise. Kanni Maadam narrates the tale of Madurai-based couple who runs for their life to Chennai as the relatives of the boy are quite enraged by their act. When both of them start a new life slowly and steadily, a tragedy hits them in the from of a road accident. Malar (Seya Devi) task quite some time to come to terms with Kathir's (Vishnu) demise, but struggles hard to come up in life when she realizes that she is going to be a mother. Two auto rickshaw drivers, who live nearby her home, come he her rescue (Sreeram and Murugadoss). How she faces various challenges from different quarters from the rest of the story.
