In modern times, a PhD in engineering travels back to become Su Hao, the cousin of the Crown Princess in the Tang Dynasty, known as 'Su the Fool.' To repay his sister Su's nurturing, he takes up dual hammers, vowing to protect her. He cures the Crown Prince's leg ailment, produces fine salt to defeat the aristocracy, designs iron furnaces to warm the harem, and refines white sugar to fill the royal treasury, using knowledge beyond his time to pave the way for his sister. In the winter hunting grounds, hundreds of assassins surround the Crown Prince, and Su Hao carries Li Chengqian and leaps off a cliff. This pair of siblings, relying on each other, protect one another in the treacherous palace, forging a path for the Crown Prince to survive and paving the way for the Su family to ascend to the position of Empress!