For Naina Catherine Kapur (Preity Zinta), life is cold, gray and dull - as it has been ever since a family tragedy shook her world. Between the constant bickering in her half Punjabi, half Catholic household, her grand-mother's temper, looking after her siblings and helping her mother Jennifer (Jaya Bachchan) deal with financial troubles - Naina has no time for parties, fun or herself. She is 23, going on 50. She is serious, she is boring.

Enter Aman Mathur (Shah Rukh Khan). Like a whiff of fresh air, he moves into their tiny Indian neighborhood to take it over, helping others solve their problems and face life's little challenges - Aman has all the answers.

Much to Naina's irritation, he insists on interfering in her life too…

Aman pushes Naina into doing things that she would never dream of doing. He nags her till she learns to smile. He conspires with friend Rohit (Saif Ali Khan), an eligible Manhattan bachelor, to help her find happiness.

Kal Ho Naa Ho is the story of Aman, Rohit and Naina's journey together. How they discover themselves, find the courage to love and come together to celebrate life.