Sona da with Aabir and Jhinuk embarks on his new adventure, a quest that will take them to the legendary Durgeshgor. The journey reveals that the Debroy family, the erstwhile zamindars in their princely mansion hold the key to a presumed rumour of a treasure connected with Plassey. With an amazing vibrant backdrop of Durga Puja in the princely Debroy mansion where the trio is invited for the occasion, one after the other clues is revealed testing Sona da`s wit and grit one more time leading towards the discovery of one of greatest treasures Bengal has ever witnessed.
Feluda and his cousin Topshe goes to Lucknow with Topshe’s father to spend the Puja vacation. They arrived at the house of Dhirendra Kumar Sanyal, a friend of Topshe’s father. That evening Dr. Shrivastav also came to Dhirendra Kumar Sanyal and tells him about last night, a thief tried to steal his ‘Ring of Aurangzeb’ (The Emperor’s Ring) which was given to him by Pyarilaal Seth. After the incident Dr. Shrivastav has been afraid and asks Dhirendra Kumar Sanyal to keep the ring safe. Dhirendra Kumar Sanyal agreed and keeps the ring to his home. But someday the ring goes missing from there. Then Feluda and Topshe started investigation for the culprit. Meanwhile, Feluda meets an interesting person in doctor’s neighborhood, Mr. Bonobihari Sarkar. Bonobihari babu has ferocious and poisonous creatures like crocodile, African tiger, hyena, rattlesnake, scorpion and black widow spider in his own home.