Joon (Kim Bum) is a superhuman - the result of an experiment by the late Dr. Bishop. However, before he is able to perfect his experiment he is captured and executed for his crimes. Without his creator, Joon is now vulnerable without any understanding of his purpose, strengths and weaknesses. Agent L (Kim So Eun) is a part of an organisation that has been monitoring the works of Dr. Bishop over the years. During the capture of Dr. Bishop, Joon was also captured. Belatedly realising Joon’s skills, they intend to observe him - believing that Joon will be of use to the development of building the country’s army and defence. L is given the responsibility of watching over him.