Detective Ji Bai and profiler Xu Xu, an unlikely duo, join forces to crack intricate cases. As they grow closer, Ji Bai's affection blossoms, but Xu Xu is oblivious until a chilling serial killer resurfaces threatening their newfound bond.

Detective Ji Bai and new criminal profiler Xu Xu may seem like an awkward teacher-student pair at first glance, yet they are actually the best partners in the police force, solving one crime after another. Ji Bai slowly falls in love with Xu Xu, yet she is a girl who is as slow as a snail when it comes to love. Just as Xu Xu starts to reciprocate Ji Bai's feelings, the dormant "Angel's Killer" reappears.