7G Rainbow Colony movie revoves around Kadhir (Ravi Krishna) who is the elder son of Vijayan is an irresponsible youth, who bunks classes, fails in his exams, go behind girls and freaks out with his friends. Upon ridiculed by his father, he picks up a fight with him.
At this moment enters Anita (Sonia Agrawal). Her family (a North-Indian one) takes up the flat 7G in the Rainbow Colony. As usual Kadhir like any other youngster in the area tries to impress her. He repeatedly goes behind her and cuts her name on his hand and tries to impress her with greeting cards and letters. But everything is futile.
He develops an inferiority complex and goes into a shell. Anita steps in to solve all his problems. She motivates him to come up in life and helps him find a job.
The latter half is all about Anita falling in love with Kadhir and her efforts to hold his hands in support. However, a series of events in their lives finally separate them and that makes the heroine to take a momentous decision in her life.