When an amateur killer's path crosses with that of a young girl, an unlikely bond is forged between them. Soon she transfers a ringtone she created to his phone, and things begin to unfold in a manner he had never anticipated.
"An unexpected act of kindness ensures that the girl is ready to extend her friendship to the man behind it. In the process, a tune composed by her ends up on his phone, and nothing is ever the same for the protagonist and his violent trade of killing."
When a person is very angry, their anger can change when they listen to music. Same way, a melodious tune or song can change a criminal’s mind and that’s how 'Dhun' evolved. The rest is fiction.