Agricultural machinery repairman Tian Shoucheng guards a broken-down shop and is mocked by the whole village as "Tian the Scrap". He spends all the money meant for repairing the courtyard wall to buy a scrapped old thresher and a box of rusted iron molds. During the autumn harvest, continuous rain washes out the roads, and all the villagers' old agricultural machinery breaks down one after another due to a discontinued part, the "No. 13 positioning lock plate". Only his box of "rotting iron pieces" can make this part. On a rainy night, the villagers crowd to his door; after reckoning with three years of grievances, he is initially disheartened and quits, but is finally persuaded to return, proposing only one condition: those who have cursed him must apologize in person. Under the lamp, he starts the machine, the scrap pieces are pressed all night, and by dawn the first qualified lock plate falls, sending the whole village into a frenzy. The rice is rushed into the yard for harvesting, and his son also returns to take over the craft.