Sun Dehai, a kind-hearted plumber and electrician in an old residential community, has spent eight years helping his neighbor, the Chen family, clear their heating pipes and repair their plumbing for free. He even risked his life late at night to take a seriously ill elderly member of the Chen family to the hospital. But Chen Hao, the family's grandson who is pursuing a postgraduate degree, reports Sun Dehai under his real name in the name of so-called rules, getting him fined. Even afterward, the Chen family continues to come asking for his help. Deeply disheartened, Sun Dehai finally refuses to help again. When a cold wave arrives and the Chen family's heating system bursts, no one is willing to lend a hand. They have no choice but to pay an exorbitant price for repairs, experiencing firsthand the heavy cost of exhausting someone's goodwill and finally understanding the boundary between human kindness and rules.