Sanjog is a romantic family drama. The movie revolves around a young woman named Yashodhara (Jaya Prada), who marries Narain (Jeetendra), and moves with him to live with his joint family, consisting of his parents, brother, Sonu (Vinod Mehra), and sister-in-law, Lalita (Bharati Achrekar). Lalita gives birth to a baby boy, Raju, but is careless about her responsibilities, it is then Yashodhara takes up the responsibility and gets really attached to the infant. However, in an accident, Raju dies, which affects Yashodhara a lot, and she becomes insane. Later, when Yashodhara gives birth to a baby girl, Asha, Narain entrusts the baby to Sonu and Lalita, and moves to the hills with his wife. The question remains, will Lalita care for Asha like her own? Will Asha ever know her real parents?