Maurice Druon's The Iron King, which was an inspiration for George R. R. Martin's A Game of Thrones, is still available in digital format for only 1.99$ here!
Here's the blurb:
‘This is the original game of thrones’ George R.R. Martin From the publishers that brought you A Game of Thrones comes the series that inspired George R.R. Martin’s epic work. France became a great nation under Philip the Fair – but it was a greatness achieved at the expense of her people, for his was a reign characterised by violence, the scandalous adulteries of his daughters-in-law, and the triumph of royal authority.