Ninaithale movie story opens with a car accident in which Rupa (Nargis) parents are killed due to carelessness of a drunken driver. She becomes an orphan but friends and neighbours support her and she gets a good job.
She falls in love with Rahul, her colleague, and she accepts to marry him. On the other side there's Anand (Suchin),an US returned guy who is forced to attend a family friend’s wedding. On the wedding day he meets the bride Rupa and its love at first sight for him. But soon the wedding is called off because of some arguments between Rupa and her future mother in law.
Anand is very happy because the marriage gets cancelled. Anand talks to Rupa and he admires her for her boldness. He completely falls in love with her. To win her love, he does lots of things like shifting his house nearer to hers, gradually developing friendship with her and finally entering into her heart. But when she starts to love him, she comes to know that Anand's father was the murderer of her parents. The rest of the story is about if the lovers will be united.