On the outskirts of the city stands a mysterious pawnshop, Number Seven. Its owner, Song Yu, coldly trades souls for the sake of his family's interests. When a man comes to pawn his soul for money, Song Yu unhesitatingly seals the dark bargain.
After hearing rumors about the pawnshop, police officer Liu Yue launches an investigation on her own. She confronts Song Yu at the shop, but can only watch as he destroys the contract. Liu Yue continues her pursuit, eventually stopping a deal at the abandoned St. Mary's Church and thoroughly enraging Song Yu. He first sends a shadowy figure to attack her. When that fails, he goes after her himself, but in the midst of their clash, an unexpected feeling begins to grow between them.
Liu Yue discovers a crucial record of the transactions at the police station. Song Yu sends people to seize it, but she drives them off. Later, Liu Yue finds an abandoned factory on the outskirts of the city that may be the pawnshop's hideout, but she falls into a trap. At the critical moment, Song Yu comes to her rescue. Together, they enter a room containing a mysterious crystal ball. The many mysteries surrounding Number Seven's trading rules, the forces behind it, why Song Yu pawned his kindness, and the purpose of the crystal ball keep readers captivated and immersed in the story.
