Set in 1957, "Alien Trespass" chronicles a fiery object from space that crashes into a mountaintop in the California desert, bringing the threat of disaster to Earth. Out of the flying saucer escapes a murderous creature - the Ghota, which is bent on destroying all life forms on the planet. A benevolent alien from the spaceship, Urp, inhabits the body of Ted Lewis (Eric McCormack) - a local astronomer - and with the help of Tammy (Jenni Baird), a waitress from the local diner, sets out to save mankind.