'Thammudu' is a family oriented sports drama that delves into the special relationship between brothers, and primarily revolves around Subrahmanyam (Pawan Kalyan), the youngest son of a family, who is a wastrel and a ladies man.
His father always scolds him but his brother Chakri (Achyuth) who is a boxer, and friend Jaanu (Preeti Jhangiani) dote him. Meanwhile he falls in love with Lovely (Aditi) and for this he keeps on telling lies to her that he is very rich.
Parallely, Jaanu his childhood friend, truly loves Subrahmanyam and gives him everything he asks her for, thinking that he is doing these for her but he does it for lovely.
The crux of the story is the coming of age drama that plots the incidents that lead Subrahmanyam to change his ways, mature as an adult, realise the true love of Jaanu and finally, prove his self worth by becoming a boxing champion.