Tan Zhao is a retired special forces soldier who has gone undercover in enemy-occupied territory during the Republic of China era. By day, he poses as a taciturn, dull-witted apprentice mechanic, concealing his talents. With enough time spent idling, he unlocks three exclusive skills: Thunder Dao demon-slaying, criminal investigation, and weapons engineering. While investigating unsolved cases linking hidden enemy agents to evil spirits, he improves weapons and arms the underground resistance around him, playing the pig to eat the tiger as he gradually cleanses the city's hidden rot.
