Gao Yi, a suona player in a folk orchestra, is a notorious "thrifty angel" whose entire life is built around extreme penny-pinching. Driven by pure greed, he agrees to temporarily look after a four-year-old boy named Awu for a quick 300 yuan. However, things take an unexpected turn when the boy's mother suddenly disappears without a trace, forcing the stingy bachelor and the toddler into becoming a makeshift father-and-son duo. Meanwhile, Gao Yi falls head over heels for a beautiful cellist named Wen Lan, launching an absurdly cheap and stingy courtship. Through a series of hilarious yet touching misadventures, Gao Yi's rigid principles regarding money and life begin to fundamentally change.

The fantastical and magnificent city of Chang'an, a city woven with gears and mechanisms, is home to both humans and demons living side by side beneath its upturned eaves. Di Shao, a genius young man aspiring to become "Chang'an's Number One Detective," possesses exceptional crime-solving skills and a sharp tongue; while Asa, a rookie wolf demon constable, is formidable in martial arts yet kind-hearted. A bizarre murder case forces these two adversaries to team up, embarking on a hilarious and bickering detective journey. As clues point to the heart of the city, can this unreliable duo protect the joyful daily life of this fantastical city? And what earth-shattering secret lies hidden behind the bustling and prosperous Chang'an?