He thought getting a certification would be his ticket to a whole new life. But Mu Jin, a labor attorney, is barely scraping by, worrying about the rent. While snooping around an industrial site with content creator Gyeon Woo and Hee Ju, his sister-in-law, Mu Jin gets in an accident. To survive, Mu Jin signs a contract with a mysterious being that appeared from nowhere. But then, he starts seeing ghosts who died unjustly. The trio forms Team Mujins to uncover the truth behind labor sites. Confronted with the horrors of reality scarier than any ghost, such as collapsing factories, absurd contracts, and stolen wages, Mu Jin walks a tightrope between survival and justice. It starts clumsily, but Mu Jin never gives up once he sets his mind to it. With relentless determination, he begins to resolve the lingering regrets of the dead. But can he truly speak for the dead and change the world?