Yan Nanfei, a modern-day transmigrator, is granted a marriage to the Duke of Wei's household under the guise of a fool. Though seemingly foolish, he secretly uses modern knowledge and technology to protect everyone amid the family's crisis and face challenges from all sides. Step by step, he earns their trust and leads his family out of hardship, transforming from someone looked down upon into a man entrusted with great responsibility. The story revolves around protection, trust, and responsibility.