Mastodawn

Just a summary:
1. Vajpayee had a long affair with a married woman and had a love child, which he never acknowledged in public. His son-in-law was a well-known power broker and lobbyist.
2. As a young man, he wrote rabidly communal articles, calling Indian muslims, even those who stayed behind in India after Partition as traitors and fifth columnists.
3. During the partition he wrote a series of inflammatory articles about Gandhi, targeted at incoming Punjabi refugees (such as Madanlal Pahwa)

Madanlal Pahwa was a Punjabi refugee from West Pakistan who was part of the team of assassins along with Godse. He was the first to make an attempt on Gandhi's life, but was caught.

The funniest bit about Vajpayee in the book is about the myth that Nehru marked him out early as a future prime minister. The author states that Nehru found the young Vajpayee to be highly offensive and his views on Kashmir to be highly objectionable, liable to cause international diplomatic embarrassment to India. This bit was probably made up in the 1990s by the RSS to make Vajpayee more palatable.