Murugesan, aged about 10, brings his infant sister to Kodaikanal, where a provision store owner Thakapan Swami Nadar (Thambi Ramiah), takes pity on the kids and gives them a place to stay. A grown Murugesan (Arjuna) is a tea stall owner who looks every bit a ruffian, talks little, does not show any emotions, has animalistic behavior, displays carnivorous eating habits, and drinks arrack in litres. The one person who is the world to him is his sister Azhagu (Sri Priyanka), on whom he dotes so much that people around call him Kangaroo. There is also Chellam (Varsha Ashwathi), a friend of Azhagu who loves Murugesan. The villain group consists of Ticket (Kalabhavan Mani), who wants to push Chellam into the flesh trade with the help of her sister, who is already in it, and a jeep driver who lusts for Azhagu. Murugesan bashes the two men for disturbing his sister and her friend, and an enmity ensues. Murugesan discovers that his sister is in love with another jeep driver Mani and arranges for the marriage between the two, much to the jealousy of Ticket and his friend.  Just before the marriage, Mani falls from a cliff and dies. After a few months, Murugesan convinces Azhagu to marry again and fixes a groom, but this groom dies from electrocution. The sibling duo moves to another town where she gets married, but an attempt on the husband too is made, injuring him severely, and the unknown killer is ready to try again at the hospital. What happens to the brother and sister and who kills off every suitor of Azhagu forms the rest of the screenplay.