Badshahi Angti (English title: The Emperor's Ring) is a novel by Satyajit Ray featuring the private detective Feluda.

In the evening, while having tea, they have a visitor named Dr. Srivastav, who is an osteopath and a good friend of Dhiru Kaka.

Dr. Srivastav tells Dhiru Kaka that last night a daku (dacoit) had broken into his house.

He believes that the dacoit must have come to rob a precious ring given to him by Pyarelal Seth, because he had saved the life of his only son.

Dr. Srivastav tells that robberies do not happen much in his neighborhood due to the presence of Bonobihari Sarkar, who owns a private menagerie with a variety of poisonous animals.

Dhiru Kaka tells Feluda that the ring once belonged to the Mughal emperor Aurangzeb.

In the roof of the Imambara, they find a man introduced by Dhiru Kaka as Mahavir Seth, Pyarelal's son.

In the evening, they come to Bonobihari's house and see his private zoo, especially three of the most poisonous creatures - a rattlesnake, a blue scorpion and a Black Widow Spider.

When they came back to Dhiru Kaka's house, his servant informs him that a sadhu baba had been waiting for him.

While coming back to the house, someone throws a rolled up paper on Feluda, who ultimately fails to catch the person.

That night, someone tries to knock Feluda and Topshe unconscious by using chloroform, but fails as they both manage to awaken and save themselves.

Next day, Feluda and Topshe travel to Hazratganj, where they meet Mahavir in a book store.

They go to a coffee shop where Mahavir discloses to Feluda that his father used to get palpitations whenever he used to see any insect.

After returning to the dharamshala, they find Bonobihari talking with another Bengali man, Bilash Babu, who claims to be an astrologer.

Feluda reveals that the "spy" which Pyarelal uttered at the time of his death meant "spider", and his assistant Ganesh was following Dr. Srivastav from day one.

Topshe regains consciousness and sees Feluda wearing the emperor Aurangzeb's ring.