Young cultural relic restorer Su Wan applies for a job at the "Ninth Secret Realm Museum" with a monthly salary of one hundred thousand. On her first night on the job, she accidentally awakens Cang Ren, an ancient artifact spirit inside an old blade. Cang Ren's obsession is to take national treasures scattered during the southward migration a hundred years ago back home. Su Wan possesses the empathetic talent to resonate with cultural relics, allowing her to see the millennia-long memories of the artifacts. From bickering to depending on each other for life and death, the human and the spirit resolve the century-old obsession of a jade hairpin palace maid. The mysterious organization "Rent Collectors" hunts down artifact spirits, and Cang Ren's spiritual body shatters and his remnant soul falls into a slumber to protect Su Wan. To awaken him, Su Wan goes to London to retrieve the national treasure — "The things were borrowed, it's time to return them."