The Swans of Fifth Avenue by Melanie Benjamin

This was a book hat I thought was frivolous until I realized that t was as much fact as fiction.  When Truman Capote was at his height as a literary celebrity, he gathered around him many of the women of New York's most prominent families - his swans.  He sailed on their yachts, lounged by the pools at their summer homes, was the life of their parties - and shared their secrets.  Searching for a story that would match In Cold Blood, he betrays their trust.  The results - tragic.