Palace Council by Stephen L. Carter

In the summer of 1952, twenty prominent men gather at a secret meeting on Martha’s Vineyard and devise a plot to manipulate the President of the United States. After literally stumbling on Castle's garroted corpse in a Harlem park, Eddie Wesley, a young and ambitious African-American writer, is afraid to identify himself to the police. An inverted cross bearing a cryptic inscription clutched in the victim's hand intrigues Wesley enough for him to pursue a trail that leads to a shadowy group of conspirators known as the Palace Council.

When Eddie’s younger sister mysteriously disappears, Eddie and the woman he loves, Aurelia Treene, are pulled into what becomes a twenty-year search for the truth. As Eddie and Aurelia uncover layer upon layer of intrigue, their odyssey takes them from the wealthy drawing rooms of New York through the shady corners of radical politics, all the way to the Oval Office.