Kang Yu-jin, a guard with immeasurable abilities, pretends to be a powerless zero while secretly manufacturing guard-enhancing drugs at a pharmaceutical company. He wants to live a quiet, normal life as an office worker, but his peaceful existence is shattered by the sudden appearance of Daniel Miller, a handsome and utterly insane S-Class psychokinetic. Now at risk of having his true identity as a guard exposed, his one and only wish is: "Please... let me quit my job!"