"Lockdown" tells the story of a particularly tense semester at a Catholic high school that ends in a faculty death and follows the lives of several characters caught in present-day culture wars. As seen through the eyes of English teacher Maggie Brennan, the novel introduces us to the school’s principal, a religion teacher and his wife, and a student. All play central roles in the plot.

McMahon’s flawed characters struggle to navigate everyday life in a story that has everything: drama, suspense, and humor.

A native of Massachusetts and a longtime resident of Alexandria, Virginia, McMahon used her experiences teaching English and humanities at Osborne High School in Manassas, Virginia, and later at Bishop O’Connell High School in Arlington, Virginia, as the background for "Lockdown". She began writing extensively in graduate school at the University of Memphis, where she became an instructor in English and ESL and published several short stories and articles about teaching.

McMahon is a member of the Ignatian Volunteer Corps, where she serves as a library aide at a local Catholic school. IVC provides the opportunity for mature men and women to serve the needs of the poor, to work for a more just society, and to grow deeper in Christian faith by reflecting and praying in the Ignatian tradition.

Over the last five years, the author carved out time to not only serve with IVC but to write and publish "Lockdown". “I love my service with IVC,” she says. “They are so careful to get us into positions that we like. I’ve recruited several people through my parish and enjoy the camaraderie and our monthly group meetings.”