Kangaru movie tells the life of Joseph Abraham, popularly called Josekutty (Prithviraj), who is an auto-rickshaw driver and is an honest guy with lots of friends. It is quite accidentally that Josekutty happens to meet a young girl (Kavya Madhavan).
In the meantime, his friend and marriage-broker Paapi (Harisri Ashokan), brings a marriage proposal for Josekutty that could solve his financial problems as the girl is from a rich family. The only hitch is that the girl has a child and Josekutty has to accept the child too.
And so he decides to meet the girl. He is told that the girl's name is Nancy and that she would be in a church with her sister Jancy, who has to approve of the match. Things move towards the marriage and it is only on the eve of the marriage that Josekutty realizes his folly.
But the very same night Nancy is found dead, hanging in her bedroom. All this leads to the building up of the climax.