This is book number 10 in the Agent Pendergast Novels series.
FBI Special Agent Aloysius Pendergast is visiting the old family home in Louisiana. Surrounded by ghosts of the past, he can't help but think of Helen--his wife who tragically died twelve years ago. But while examining her possessions, he makes a startling discovery--one that leads him to believe Helen's death was not accidental.
With the help of his trusted friend Lieutenant Vincent D'Agosta, Pendergast embarks on a quest to uncover the mystery of his wife's final days. It's a journey that takes him deep into the dark heart of her past, to a hidden obsession and secrets that some people would do anything to protect. But as the hunt for Helen's murderer ventures into the Bayou, Pendergast find himself faced with a killer question: just who was the woman he married?