Having given up on life, 15-year-old Chise Hatori sells herself at an underground auction, where she is bought by Elias Ainsworth, a not-quite-human mage, for 5 million pounds. She learns that he intends for her to be his future bride, and her world begins to change.

Few people know the truth about the bookstore on the outskirts of London that Elias frequents. He takes Chise there, where they meet Angelica, who teaches Chise a little bit of magic, but... The true power of the Sleigh Beggy materializes a fragment of Chise's memories.