The background
The Secret of the Nagas (Westland, pp.396, Rs.295) is the second book in the Shiva Trilogy by Amish. The Trilogy is based on the premise that Shiva was not a mythical God, but an ordinary human being who became a God because of his karma. The 3 books in the Trilogy trace the journey of Shiva from a human being to that of a God.
The Immortals of Meluha is the first book in the series. It follows the journey of Shiva from his beginnings as a Tibetan tribal leader to that of an immigrant to Meluha (the area that we now know was the site of the great Indus Valley Civilization) to becoming aware of the extraordinary destiny that awaits him and his first attempts at fulfilling that destiny. For more on the first book, you can read my review right here.
The story
The second book begins in Ayodhya with yet another skirmish between Shiva and Sati, and the Naga, who Shiva suspects was responsible for the death of his friend, Brihaspati. Yet again, the Naga escapes. By now Shiva is obsessed with hunting down the Nagas (an ostracised community of deformed beings with extraordinary skills, power and strength), and particularly that one specific Naga.