Manu revolves around a love story between two individuals from contrasting backgrounds. Sreeyuth, a young man from a modest family, falls in love with Reshma, the daughter of a wealthy household. However, their relationship faces strong opposition from her father, Vijay Selvam, a caste-conscious politician. Defying his resistance, the couple elopes and gets married, triggering intense anger. What Vijay Selvam does next, and how events unfold afterward, form the crux of the story.