When an extraterrestrial visitor arrives on Earth, his first impressions of the human species are less than positive. Taking the form of Professor Andrew Martin, a prominent mathematician at Cambridge University, the visitor is eager to complete the gruesome task assigned him and hurry back home to the utopian world of his own planet, where everyone enjoys immortality and infinite knowledge.
He is disgusted by the way humans look, what they eat, and their capacity for murder and war, and he is equally baffled by the concepts of love and family. But as time goes on, he starts to realize there may be more to this weird species than he has been led to believe. Disguised as Martin, he drinks wine, reads poetry, and develops an ear for rock music and a taste for peanut butter. Slowly, unexpectedly, he forges bonds with Martin’s family, and in picking up the pieces of the professor’s shattered personal life, he begins to see hope and beauty in the humans’ imperfections and to question the mission that brought him here.