Bhoominathan idolises Muthuramalingam, a rich powerful landlord in Semmanur. At the request of his parents, Bhoomi accepts to work for Muthuramalingam as his bodyguard. Muthuramalingam's rival is baying for his blood as his daughter committed suicide, as Muthuramalingam's son rejected her proposal. While Bhoomi protects Muthuramalingam, his rival threatens the life of his daughter Meera. No one accepts Bhoomi and he attacked Meera's brother, thus making him fired from the job, but Bhoomi saves Muthuramalingam from an attack and finally regains his job. Bhoomi is sent to college along with Meera and her friend Madhu to protect them from the threat.

Bhoomi joins the same class where Meera studies, as he has previously discontinued his education. Meera does not like Bhoomi following her as a bodyguard, and plans to divert him. Meera calls Bhoomi over his mobile phone from a private number and introduces herself as Ammukutty. Initially, Bhoomi hates the mobile call as it will disturb him, but later develops a liking towards Ammukutty and slowly love blossoms for Bhoomi without knowing that it is Meera herself. He saves Meera from an attack from Muthuramalingam's rival. At one point, Meera too feels herself develop liking towards Bhoomi and expresses her desire to meet him in person without revealing her identity. Due to circumstances, they are not able to accomplish this, and she decides to elope with Bhoomi for which he agrees.

However, Muthuramalingam learns that Bhoomi and Meera are going to run away and sends his men to stop him. Bhoomi thrashes them up easily but Muthuramalingam thrashes Bhoomi. Meera overhears her father's plans and decides to save Bhoomi by lying that he is in love with some other girl and has planned to elope with her. Muthuramalingam spares Bhoomi, believing that Meera is not his lover, but sends his men to the railway station to find out Bhoomi's lover. He also instructs that Bhoomi should be killed if there is no one in the railway station. In a desperate attempt to save Bhoomi, Meera comes up with a plan and requests Madhu to go to the railway station and pretend to be Ammukutty, so that Muthuramalingam's men will spare Bhoomi believing Madhu to be his lover.

Meera also gives a mobile phone to Madhu and informs to give it to Bhoomi when she meets him (as Bhoomi's phone is broken) so that she can reveal the truth to Bhoomi. Madhu agrees and leaves to the station. At the station, Bhoomi gets surprised seeing Madhu in the station and believes that it is Madhu, who was pretending as Ammukutty so far and hugs her. Muthuramalingam's men see this and leave the place, believing that Meera is not Bhoomi's lover. Suddenly, Madhu gets a call in the mobile given by Meera. Madhu understands that the call is from Meera and she wants to speak to Bhoomi. However, Madhu throws away the phone from train, following which it is revealed that Madhu also likes Bhoomi, and she decides to marry him by betraying Meera.

10 years later: Bhoomi is now a high-ranking I.F.S. officer, who returns to Muthuramalingam's village for a short vacation before leaving to Australia, along with his son Sidharth. Muthuramalingam's condition is ill and Madhu had died a few years back due to some medical ailments, but she has written all the truth in a diary and gives it to Sidharth to read it after her death. Sidharth has learnt all the truth. Madhu has also mentioned in the diary that this truth should never be disclosed to Bhoomi. Meera stays with her father, and Bhoomi gets shocked to know that Meera still remains unmarried.

When Bhoomi and Sidharth are about to return home, Sidharth asks Meera to come with them and expresses his wish to call her as his mother. Bhoomi berates Sidharth for his suggestion and apologises to Meera and Muthuramalingam, but Muthuramalingam also insists Meera to leave with Bhoomi. Bhoomi, Meera and Sidharth leave together from the village. Just the before the train starts, Sidharth throws the diary containing the truth in a dust bin and comes back, but Bhoomi takes back the diary from the dust bin, without Sidharth's knowledge. Upon reading the diary, Bhoomi is shocked knowing it was Meera who loved him in the name of Ammukutty and wholeheartedly accepts Meera.