Devious - Lisa Jackson

In #1 New York Times bestselling author Lisa Jackson's riveting novel of heart-stopping suspense, a woman races to discover the truth about a convent filled with unholy secrets.
The crime scene at St. Marguerite's cathedral in New Orleans is shocking, even to seasoned detectives like Rick Bentz and Reuben Montoya. A novice nun named Sister Camille has been found dressed in a yellowed bridal gown and viciously garroted, her body covered with an altar cloth.
Valerie Houston is devastated by her sister's death. For weeks, she'd begged Camille to leave St. Marguerite's, where she seemed determined to live as some kind of martyr. But Camille had a knack for making bad choices—she joined the convent in part because she'd fallen for Val's soon-to-be ex-husband, Slade.
Convinced the police aren't doing enough, Val begins to investigate. Slade, on a mission to repair their marriage, is determined to help her. But the deeper Val's inquiries go, the more twisted the case becomes. St. Marguerite's is far from the tranquil retreat many believe, and everyone, from handsome Father Frank O'Toole to the mysterious Mother Superior, has their own agenda. Despite their closeness, even Camille had a hidden life Val never suspected. But someone knew about Camille's past—and Val's, too. Now she has no choice but to catch a devious, depraved killer intent on purging St. Marguerite's of all its sins—before she becomes the next victim. . .