Colonel Mahendranath falls a victim to his own suspicious nature, when he drives his wife, Jamuna, out of the house on a baseless allegation. They had a two years old son Mohan. As Colonel would not have her back she succeeds to get her son through the help of Kapur, a stranger, in exchange for all the jewelry on her person and leaves for an unknown destination. Colonel's attempt to catch Kapur, while kidnapping the child, is foiled by their car's accident in which Dr.Prem, a friend of Colonel, is killed. Soon after, Colonel repents for his baseless suspicion against his wife and tries to get her back without any success. The dejected Colonel adopts Dr.Prem's only daughter, Mohana, and starts his life a-new. Years go by and Mohana is now a grown-up girl.
Mohan brought up by his mother in Kashmir, comes to visit Delhi with his friend. In a coffee house, he meets Mohana and immediately recognizes her, as he knew all about his father. Both get friendly and roam about the whole of Delhi and Agra. By dusk, they realize that in one day they have come too close to even think of separation. The next day Mohana has to go to Kashmir with her friends to participate in a Youth festival, and Mohan also returns to Kashmir. Both meet in Kashmir again and their love reaches its climax when fate turns against them. In Delhi, the old crook Kapur meets Colonel and informs that his son is in Kashmir and his mother's death has shocked him to madness.
Colonel goes to Kashmir and meets the young man. His name is Ramesh but he has got the same locket around his neck which Mohan used to wear as a child. Colonel is very happy to meet his son. Receiving Mohana's presence and care, Ramesh improves. Colonel is convinced that his son needs Mohana's love and affection.
His firm decision that Mohana must marry his invalid son and the cunning treacherous game played by Kapur and his accomplices on one side and the endless deep love between Mohan and Mohana on the other. To see the victor of this battle of wits will be your life's experience when you will see "PHIR WOHI DIL LAYA HOON".
[from the official press booklet]