As an alien tasked with annihilating the human race arrives on Earth, he impersonates a doctor from a small town in Colorado, whereupon he becomes conflicted about his mission. Moreover, he discovers that a young boy can see his real extraterrestrial identity.
In the second season, Harry returns to Earth but does not remember who he is and seeks help from Asta. Also, he must attend a poker game before implementing the rescue plan and meets a woman who turns out to be the key to his new mission.