Vembu tells the story of a spirited village girl with a deep passion for martial arts. Raised by her supportive father, she dreams of excelling in martial arts while preparing for government exams. Pressured by society, she agrees to marry her cousin Vetri. Understanding her inner conflict, Vetri promises to support her dreams. As financial struggles arise, Vembu steps up to take care of the family. The film portrays her resilience and determination to rise above challenges and pursue her passion.