Lin Guodong, the last master carpenter of the Lin family, guards the century-old ancestral hall but is insulted as a rotten piece of wood and a useless relic. A contractor who won the bid with an unusually low price cuts corners, rushing the work with steel nails and quick-drying glue while claiming that traditional craftsmanship is long outdated. When the rainy season suddenly arrives, the ancestral hall's roof framework collapses with a thunderous crash. At this critical moment, Lin Guodong uses his family's ancestral mortise-and-tenon techniques to dismantle and thoroughly restore the structure, saving the century-old historic building and breathing new life into traditional construction techniques that were on the verge of being lost.