Deep within the isolated Gulab Bagh Estate in the foothills of Udaipur stands the Sheesh Mahal Conservatory—an impenetrable glass pavilion converted into a high-security vault. Enclosed by an artificial lake, monitored by thermal sensors, and locked from the inside, it holds the legendary 72-carat Karkotaka Diamond.
Four distinguished specialists—a gemologist, a chemical analyst, a structural engineer, and a royal historian—are summoned to perform a midnight authentication of the stone. But during a brief four-second power failure, the impossible occurs: historian Professor Dev Acharya is murdered, the diamond vanishes, and yet the vault doors remain double-bolted, the glass display dome untouched, and the alarm silent. Written as a classic fair-play whodunit, the story presents every clue, diagram, and timeline detail needed for the reader to solve the crime alongside the detective.