Lin Lang transmigrates to a fantasy world, finding himself a live-in son-in-law at the Zhao manor. Expecting a life of endless humiliation, he is unexpectedly bound to a divine-grade animal evolution system. With its help, his seemingly ordinary animal companions undergo incredible transformations. "Ding! Your assassin fly has strengthened its two claws, now equipped with metal weapons, sharp as blades!" "Ding! Your pet spider has completed its evolution, gaining a special skill: lethal venom!" As Lin Lang's animal army grows stronger, a mysterious assassin organization rises in the world. Using these evolved creatures as their unseen pawns, they execute their targets with deadly precision, leaving no trace behind.