Ethaniel is an alien hitman who has come from a far away planet, adopting a human guise in pursuit of a rogue named David Banning, whom he intends to capture and bring back home with him. Aided by brilliant therapist Dr. Laura Keating, who shares a mutual attraction with Ethaniel, and the impetuous Byder, he must learn the ways of Earth and the practices of its inhabitants, as he seeks both Banning and his brother, Thorber, a scientist who worked with Banning before Banning announced his intention to destroy Earth in its entirety.