The Gentlest of the Brothers, by David Alexander (epub/Kindle/pdf)
Kevin McCarthy, lay brother at a seminary, learns of the suicide of Rose Kathleen, his sister. She had been an exotic dancer and prostitute for a childhood bully turned crime lord, Rory O'Bannon. In her suicide note, she also sent Kevin a diary naming names, detailing narcotics transactions, and prostitution activities. Kevin renounces his vows, confessing to his superior his plan to kill Rory O'Bannon...