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.
Harry is on a mission to rid Earth of gray aliens while struggling to balance work and his personal life after he falls in love for the first time.
Mike tries to assist Harry after learning that the aliens are real, while the actual Harry's friends try to find a method to rescue him from the grasp of the baddies led by Grace. The phony Harry causes a lot of turmoil.