Rita, the young and modernised daughter of Rai Bahadur Chunilal Khanna returns from America after finishing her studies. Rai Bahadur and his wife think it is time for Rita to get married and settle down. Rita, however, requires sometime of leisure to decide about her future.
Rita comes to Srinagar and stays in a houseboat - which belongs to Raja, a young, happy go lucky, simple minded and simple hearted, uneducated but honest man. For Raja it is love at first sight but since he is poor and uneducated, whose life is to serve the likes of Rita, he cannot express his love to the so rich, so beautiful and so dignified Mem Sahib.
Rita, nevertheless, is intrigued by the simplicity and innocence of this grown up child of nature. She takes interest in him and tries to educate him. Raja is happy - he has an excuse to be near the one he loves.
But Rita is just another tourist to Kashmir. One day she goes back leaving Raja sad but hopeful that his Mam Sahib may, one day, come back to Kashmir.
And Rita does come back to Kashmir - but with Kishore, the choice of Rai Bahadur and Mrs. Khanna for their daughter.
Raja is happy - his Mem Sahib has come back and is still the same - friendly and affectionate - but Kishore cannot understand how Rita can be so friendly towards one who he considers to be a menial. Rita hates snobbery - specially in a person whom she is getting engaged to. She gets more friendly with Raja -specially when in an accident he saves her life.
Rai Bahadur Khanna also comes to Srinagar and misunderstands Rita's friendship with Raja - he takes her back to Bombay forcibly.
Raja follows Rita to Bombay and defiant Rita tells her father that she will marry Raja - even if she had to spend her whole life bringing him upto the standard of modern society.
Raja is educated by Rita, he is intelligent and learns the ways of west - and finally he is introduced one day to the cream of society.
But Raja finds that the cream of sour - that East is East and West is West and Jab Jab Phool Khile is the story of East and West and where and how they meet.
(From the official press booklet)