May Agnes Fleming - Midnight Queen

May Agnes Fleming is renowned as Canada's first best-selling novelist. She wrote 42 novels, many of which have only been published posthumously.
The Midnight Queen is set in London, in the year of the plague 1665. Sir Norman Kingsley visits the soothsayer «La Masque» who shows him the vision of a beautiful young lady. Falling madly in love with her, he is astonished to find her only a short time later and saves her from being buried alive. He takes her home to care for her, but while he fetches a doctor, she disappears. Sir Kingsley and his friend Ormistan embark on an adventure to solve the mystery of the young lady — will they ever find her again? (Summary by Availle)