Perri O’Shaughnessy is the pen name of two sisters from Southern California. Pamela O’Shaughnessy graduated from Harvard Law School and practiced as a sole practitioner in South Lake Tahoe for sixteen years. Mary O’Shaughnessy studied English literature at UC Santa Barbara and worked in multimedia publishing near San Francisco. Their pseudonym combines their own names with a nod to Perry Mason, the fictional lawyer they grew up reading about.
Their main body of work is the Nina Reilly series, thirteen legal thrillers published between 1995 and 2011. The books follow a single-mother attorney navigating cases in the Lake Tahoe area, drawing heavily on Pamela’s firsthand experience practicing law in that community. The series hit the New York Times bestseller list multiple times. Outside of Nina Reilly, they published a standalone thriller, a short story collection, and a legal anthology contribution.