Masoom is a family drama that revolves around a man named Devendra Kumar (Naseeruddin Shah), who is an architect and lives with his wife and two daughters peacefully in New Delhi. However, their happy and peaceful life faces a turbulence, when Devendra learns about his illegitimate son, Rahul (Jugal Hansraj). Rahul’s mother dies tragically and Devendra takes him under his care. His wife is reluctant about it and continues to stay cold with Rahul. Will Rahul be able to develop a warm relationship with Devendra’s family?