Born into a family of carpenters, Lin Qiao'er works at Qingyin Pavilion to repay her father's debts, but she has never abandoned her family's ancestral mortise-and-tenon craftsmanship. When a century-old library faces imminent collapse and no one knows how to repair it, she seizes the opportunity and takes on the restoration challenge with her family's nearly forgotten skills. Despite repeated interference from a spoiled young master and society's prejudice against women, she uses her ingenious techniques to join wood without a single iron nail, breathing new life into decaying timber. From working off her debts to gaining her freedom, from being dismissed by everyone to opening her own woodworking workshop, she uses mortise-and-tenon joinery as her foundation to carve out a legendary life of her own.