An ancient bell traps a mountain village and a well of calamity inside a boundary. The boundary gate opens for only seven days once every ten years. The immortal sects come to the village to choose people, and those selected never return.
Chen Ye is the village blacksmith, and he has no spiritual roots. After his younger sister is written into the register, he hears a crack inside the seal, saves the others in the same carriage, but fails to save her. Armed with his father's old hammer and the bell clapper, he chases after them to the boundary gate's altar. Using only his mortal body, he withstands thunder and fire, forging the first black blade.
His sister survives, but is marked by the calamity. Within forty-nine days, he must enter the immortal sect and find the spirit pool that can cleanse the mark. The sect secretly uses young people's spiritual roots to forge calamity iron. Starting as a servant, Chen Ye follows the clues left by the missing and forges calamity into a blade he can hold in his hand.
