Qin Yun, a crippled man with an ordinary physique, is granted a marriage to Tang Guiyao, the female war goddess who protects the nation, by the Female Emperor. On his wedding day, he activates the Invincible Lie-Flat System. As long as he maintains his marriage, he can claim extraordinary rewards through daily check-ins. On the first day of his marriage, he receives the Supreme Bone, and from then on rises from a useless son-in-law mocked by everyone. He pretends to be weak and lets others beat him while secretly protecting the Tang family—saving his sister-in-law when she falls into demonic possession, venturing alone into Mount Tai's forbidden zone to rescue the heroine after her demotion, and furiously slaying nineteen prodigies from the sacred lands. Facing the Female Emperor's suspicions and the joint pursuit of the sacred lands, he finally stops holding back. With the power of a Half-Saint, he slays the ruler to establish his might and ultimately embarks on the path to becoming the Human Emperor, protecting the human race of the Nine Provinces.