Hum Kisi Se Kum Nahin

The story begins with a wealthy man selling his entire estate in Africa, converting it to diamonds. He carries them in a belt. He suffers a heart attack in the washroom and requests a passerby to deliver the diamonds to his son, Rajesh (Rishi Kapoor).The man is chased by goons who are after the diamonds. He hides them in a bicycle toolbox.

The bicycle belongs to Sanjay Kumar (Tariq Khan), who is unaware that his bicycle has 25 crore rupees worth of diamonds hidden in its toolbox. Saudagar Singh (Amjad Khan) is after the diamonds. He and his partner Ranbir Kumar Dana set a trap for Rajesh telling a false story to him.The whole plot is speedy after that with Rajesh pretending as Manjeet Kumar Dana is to fall in love with Kajal (Kajal Kiran) who is in love with her childhood love, Sanjay. There are a series of meetings between the two.

A few years ago when motherless Kajals father Kishorilal was in deep financial crisis, Sanjays father gave shelter to him, who has now become filthy rich. The promise of getting Sanjay and Kajol married is forgotten when Kishorilal insults them and forgets the promise that was made years prior. To unfold the plot, Sanjay becomes Manjeets manager. Saudagar uses Manjeet to get the diamonds himself in the climax.