Lin Mo, a modern engineer, transmigrates and becomes a condemned prisoner in the Yue Kingdom. Using modern military technology, he rises to deputy workshop master of a weapon forge. His former mentor Zhao Fangming, another transmigrator, plots a rebellion. Lin Mo pretends to surrender, secretly building fatal flaws into the firearms, and sends intelligence through different forces. He finally detonates the rebel artillery, helps the Yue Emperor crush the revolt, and retires to the mountains with his wife Mo Ling.
