Sanjog is a story about Bombay-bred Narain who falls in love with a village belle named Yashodra. They get married and move in with Narain's family, but Yashodra becomes very close to Narain's nephew, Sonu. This causes tension with Lalita, Narain's sister-in-law. Tragically, Sonu passes away, sending Yashodra into a deep depression. She gives birth to a daughter but remains fixated on Sonu, leading to her institutionalization due to insanity.
Narain turns to alcohol to cope with his grief, while their daughter is adopted by Lalita and his brother without knowing her true parentage. Years later, their daughter Asha, now a mother herself, visits India and discovers the truth about her parents. She finds Yashodra in a state of delusion, holding a piece of log and singing to it as if it were Sonu. Asha must now make a difficult decision that will test her love and loyalty.