Many people have the superpower of seeing something invisible. Jia-kai can't see ghosts, but he can see the different colored threads connecting people. The more threads, the more bonds a person has. Jia-kai has seen countless threads, but he hasn't been connected to anyone at all. He can't figure out why but has accepted himself as a loner. However, because of a chaotic incident, he meets a policeman named Da-wei and realizes that one silver-grey thread has grown from him to him, connecting them together! Jia-kai doesn't want to lose the connection, so he takes a part-time job at the police station to get closer to Da-wei. With his superpower, he helps with cases of missing people and objects. They get to know each other better, and the thread between them begins to change color, from silver-grey to yellow, representing friendship, and even to red, representing love. Seeing these changes, Jia-kai realizes that how they feel for each other can't be hidden anymore...