Bodyguard revolves around young Jayakrishnan, who has a very strange habit; he adulates anyone with a trace of heroism. Whenever he develops an admiration towards a person, he prefers to move with that person as a sort of bodyguard. He starts admiring Ashokan, a former liquor tycoon and leading businessman. Jayakrishnan wants to be Ashokan’s bodyguard, but Ashokan does not need a bodyguard. Later, Jayakrishnan approaches Ashokan with a recommendation from someone he cannot refuse. He achieves his luck after saving Ashokan from danger.
Jayakrishnan thus becomes the bodyguard of Ashokan’s only daughter Ammu. Jayakrishnan follows Ammu to her college as her bodyguard. Ammu and her friend Sethulakshmi gets irritated with him following them all day.
Jayakrishnan takes his role as bodyguard very seriously and follows the two girls around constantly. In an attempt to get rid of him, Ammu and Sethulakshmi make up a “fake lover” hoping to distract Jayakrishnan from his duties as a bodyguard. It works! Jayakrishnan falls in love with “PRIVATE NUMBER”, and is constantly looking for this girl. He has no idea that his lover is Ammu. Ammu, as a joke, calls Jayakrishnan and speaks badly about Ammu. Jayakrishnan gets a little angry and disagrees with her. He believes Ammu is a good-hearted person. That’s when the viewer is able to tell Ammu is really falling in love with Jayakrishnan. This is no joke anymore. Ammu, later tells Jayakrishnan to run away with her and meet her at a railroad station. Jayakrishnan agrees, not knowing that the girl is Ammu. Ashokan finds out and he believes that Jayakrishnan and Ammu are planning to run away together. In order to save Jayakrishnan’s life, Ammu lies that it’s not her. That Jayakrishnan is meeting another girl at the station. Ashokan lets Jayakrishnan go, but tells others to kill Jayakrishnan if a girl does not show up. Terrified, Ammu sends her friend, Sethulakshmi, to the station and tells her to tell Jayakrishnan that Ammu is the lover and she won’t be able to make it to the station. Sethulakshmi, seeing Jayakrishnan, falls in love, and admits that she is the lover, not Ammu. Ammu calls her twice, but Sethulakshmi throws the cellphone out, trying to erase Ammu out of their love life completely. Years later, after Jayakrishnan and Sethulakshmi’s marriage, she bore a son. Before her death, she leaves a diary for her son telling the whole story between the phone calls and his father and Ammu. The son later goes to Ammu’s house with Jayakrishnan to visit Ashokan. Jayakrishnan is shocked Ammu isn’t married. The son asks Ammu to become his mother and Jayakrishnan is shocked and angry at his son for saying something so blunt and rude. But Ashokan begs Jayakrishnan to take Ammu as his wife. So they go onto the train together but the son runs and throws the diary into a trashcan nearby. Jayakrishnan finds the diary and realizes that his real lover, the girl who’s waited for him for so many years faithfully, was Ammu. And they live happily ever after.