Modern person Ning Chen transmigrated into a fantasy world, becoming the "useless matrilocal son-in-law" of the town-guo female valkyrie An Nanjing, suffering all kinds of mockery. But possessing a lying-flat system, the more he lies flat, the stronger he becomes, secretly transforming into a mysterious martial god, protecting the An family, beheading the fatuous emperor, destroying the Blood Cloud Pavilion, and sweeping across the nine dynasties. Younger sister-in-law An Beixue was abducted, he stormed the Qiankun Holy Land, counter-slaying the holy king, achieving the ultimate saint, and sending a second avatar to shatter the void, killing into the great world to save people. Seemingly a useless son-in-law, actually an invincible big shot, twists and face-slaps, crushing all the way, thrill maxed out.