Chen Mancang pushes his father's coffin up the mountain to bury him, only to be blocked by a blue-black winged serpent. The serpent urges him to hurry home and divide the family property, leaving behind a broken grain measure on the roof beam and a lame old hen in the courtyard. After being driven out with nothing, a single grain falls into the measure, and the next day it miraculously becomes a measure full of grain. As famine approaches, his mother falls gravely ill, grain merchants hoard supplies and raise prices, and greedy relatives steal the treasure measure. Chen Mancang uses the measure to duplicate grain and miraculous medicine, saving Su Wanhe and giving starving villagers hope of survival. But when the treasure measure falls into the hands of evildoers, a talking black grain reveals an old case of land seizure and stolen deeds. Facing bottomless greed, he must reclaim the treasure measure and protect the people's food supply.