Nombarathi Poovu movie is all about the deep relation between Gigi and Padmini. The movie shows how a young woman Padmini who is separated from her husband gets attached to a young orphan girl Gigi when they meet in a hospital during their stay after a bus accident. Gigi has lost her mother in the accident and Padmini decides to take Gigi with her. Gigi is not completely mentally stable and is a special needs child. Padmini brings Gigi to Dr. Padmanabhan who after initial apprehension accepts Gigi in his institute as a student by the day. Padmini's separated husband Sethu is still trying to win her back. The viewers are shown that Padmini separated from her husband because she lost her children due to an episode of reckless motorcycle riding from husband. Padmini decides to go back to Sethu and adopt Gigi as their daughter. However Gigi's special behavior annoys Sethu and Gigi starts to feel insecure about losing her mother again.