Parnassus on Wheels is Morley's first novel, about a fictional traveling book-selling business. The original owner of the business, Roger Mifflin, sells it to 39-year-old Helen McGill, who is tired of taking care of her older brother, Andrew. Andrew is a former businessman turned farmer, turned author. As an author, he begins using the farm as his Muse rather than a livelihood. When Mifflin shows up with his traveling bookstore, Helen buys it-partly to prevent Andrew from buying it-and partly to treat herself to a long-overdue adventure of her own.