Mahasagar is based on the ocean of feelings evolving in the human mind. While marriage is one holy and delicate institution, it can devastate any individual if infidelity creeps in. Once the trust is broken, it creates havoc. Two friends Digambar and Sumi are married with their respective spouses and stay with their family. Digambar’s wife Champu hates his brother who is mentally unstable resulting in conflicts between them. Sumi is married to Ghanshyam but has an affair with her boss Rehman. What will be the consequences when Ghanshyam comes to know of his wife’s affair?