Two very different investigators take on a string of baffling cases together. Qian Cuo is a criminal investigation captain with a short fuse, while Teng Ruiyu is a brilliant detective with a cold, detached manner. Their partnership becomes a clash of hot and cold, emotion and logic, as they solve case after case, until a chain of alchemy crimes from two years earlier draws them in. The ONA blends drama, mystery and supernatural elements.