Kannukkul Nilavu starring by vijay and shalini. Gautam Prabhakar (Vijay) is searching for Gayathri (Kaveri) who was an innocent girl that kept coming to him for help of many sorts. He comes across Surya and Chandra (Charlie and Dhamu) and Hema (Shalini). They try to cheat Gautam (like many others) but fail in doing so. Hema finally realizes that he may actually have a disease. She and her father, Dr. Rajsekhar (Raghuvaran) try to help him out. After examing his's subconscious mind, Raghuvaran finds out that he's suffering from split personality and has forgotten a lot of things.
Raghuvaran finds out that he has not come to Pondicherry in search of Gayathri but he's looking for Shanmugham ("Thalaivasal" Vijay) and his two friends, Sounder and Prakash ("Nizhagal" Ravi) whom Gautam feels have killed Gayatri, but who is actually still alive. Hema and her father don't cure Gautam right away, fearing that he may become incurable if he realizes the truth and becomes a killing maniac. Hema falls in love with Gautam. His mother (Srividhya) is worried about her son's situation, so she comes to where he is at.
Because of the love shown by his mother, Gautam slowly recovers all the missing details about why and how he got to where he is. He sets off to kill the three people and succeeds in gathering two of them. However, due to him wanting all three of dead at once and a plan made by the entire crew, Gautam realizes the truth. Gautam starts a new life with Hema after his mother and her father's acceptance.