Zhao Chuan is the most inconspicuous boy in the fishing village. With both parents deceased and debts piled high, he swings a sledgehammer in the mines to make a living, oppressed by his second uncle Zhao Jinbiao so heavily he can barely lift his head. An emerald-green frog brings a bizarre prophecy: tomorrow you will unearth a flood dragon at the bottom of the mine. The next day, a Zhenhai flood dragon—suppressed for a millennium with its whiskers jammed in a cliff crevice—floats up from the depths of the pool. It brands a blue mark on Zhao Chuan's palm, lending him dragon power, at the cost that the more he borrows, the more scales will cover his flesh and blood.