Susan Mattern spent six years as a nun in the late 1960s in St. Louis and this has formed the background for the new Who Nun It? Mystery Series. Old Habits Die Hard is the second in the series. A classical musician for most of her life, since retirement, Susan has published two ebooks. The first, Out of the Lion's Den, won the Writer's Digest Grand Prize in 2024. The second book, Poverty, Chastity, and Disobedience, is a memoir about her six years in a Catholic convent.