Kalaiyan's world revolves around his sister, Thanga Meenatchi, whom he had to raise himself after their parents died. When she returns home after completing her education in the north, some members of their family feel that it’s time to get Meenatchi married, and they convey the same to Kaalaiyaan. Unsure of the suggestion, he consults with his sister about the idea, and she tells him that it’s his decision that matters the most to her. Kaalaiyan initially has trouble finding a suitable groom, but finally agrees to let Meenatchi marry Nattadurai's younger brother. The day of the wedding, Meenatchi goes missing, so Kaalaiyan dispatches men to search the entire countryside.
They finally find Meenatchi on a train, trying to elope with a boy she met during her studies. Torn between his need to save his family's dignity and his love for his sister, Kaalaiyan finally allows Meenatchi to leave. An understanding Nattadurai peacefully leaves, and Kaalaiyan staves off demands for an honor killing from relatives. Meenatchi shifts to Kolkata with her husband, where she loses contact with Kaalaiyan. Worrying about her well-being, Kaalaiyan and Pattamal travel to Kolkata to find her. Kaalaiyan accidentally eavesdrops on Meenatchi, when he finds out that she is having serious troubles and can't bring herself to contact her brother unless she is happy and financially secure.
Kaalaiyan secretly follows Meenatchi to a bar where she meets a gangster who loaned her money to tell him that she can't pay him yet. When the gangster tries to assault her, Kaalaiyan grows enraged and beats up the man and his men.