Arun and Joshika return to their village after completing their education at the city. Arun's father is the head of the village, and people respect him out of fear, as he is a racist and give out extreme punishments and death penalties if people of lower and higher cast interact. He treats and regards people depending by their cast and class. He is so villainous and driven by racism that he once murdered a local worker just because he saved Arun's mother's life, who by mistake fell into a well. 

Arun who knows about his father's craze over practise of casteism and racism, doesn't know about the extend that he goes to implement those. Meanwhile, he falls in love with Joshika, who is from a poor background, but is a brave outspoken girl. In the due course she starts to reciprocate his feelings too. The rest of the plot revolves around how they convince his father and a secret which shakes the couple.

The film's main leads Arun and Joshika, has delivered a convincing performance, though the latter's acting could have been better. V Vedajiipandian has attempted to make village centered film which talks about how people are driven with the need to practice casteism, and how racism blinds a person. 

Though the concept is an age old story, the movie could have been loads better, as both Vedajiipandian's screenplay and direction are below average. John, MV Raghu and Shankar Ganesh has handled the music department, and the songs are tasteless compared to the ok-ish background score. Ravindran's cinematography skills comes to the fore and he his shots are decent.

In short, Tharisu Nilam, is below average.