In the heart of Qingdu City, a strange partnership takes shape between fire investigator Yu Tong and detective Lin Yao Yao after a string of odd fire incidents. They team up after a spontaneous combustion at a university campus, and soon, they're diving into a bunch of puzzling fire cases. With Yu Tong's special four-colour vision and Lin Yao Yao's sharp detective skills, they tackle the human dramas and social issues behind each fire they investigate.

As they unravel the truth behind the fires, Yu Tong's hidden intelligence and grudge-filled past come to light, challenging Lin Yao Yao's by-the-book approach. Their differences cause tension, but as they learn more about each other, especially Yu Tong's painful history, they come together to seek justice. They face their own demons and uncover some shocking truths, including the surprising revelation that Yu Tong's girlfriend's brother is their ultimate foe.