Book excerpt: Reclusive antiquarian bookseller Alan Redgrave meets Fei Yun, a beautiful and beguiling Chinese artist, at a gallery in the summer of 2018. She takes him to the ancient oasis town of Dunhuang, gateway to the Southern Silk Road. Her deep involvement with Taoist philosophy and ritual, including talismans, and her fascination with an eighteenth-century portrait lead him to wonder if there is something haunting her — or him.