Photographer Helmut Ungar, a foreign national, shows Feluda the picture of the missing Yamantaka. Parallelly, police officer Rinchen Gonpo gets suspicious of Feluda and Topshe as their investigation intensifies.
Selvankar's employee Sashadhar Bose entrusts his boss's murder investigation to Feluda. On the other hand, the Mumbai police have a new suspect named Ashwini Kaviraj.
Feluda and Topshe, along with Nishikanto, Helmut, and Sashadhar, reach Lakpa Lodge, only to realise that Dr. Vaidya is missing. However, to their surprise, his walking stick is left behind.
Rinchen is stuck trying to find the Yamantaka and arrests Helmut on suspicion. Feluda and Topshe try out an experiment to solve Selvankar's murder mystery.
With businessman Selvankar's accidental death, an invaluable idol of the Yamantaka, goes missing too. The Mumbai police also discover a drug connection with Selvankar's perfume company S.S. Chemicals.