An alien is left behind on Earth and saved by the 10-year-old Elliott who decides to keep him hidden in his home. While a task force hunts for the extra-terrestrial, Elliott, his brother, and his little sister Gertie form an emotional bond with their new friend, and try to help him find his way home.

A police chief in the war-torn streets of Los Angeles discovers that an extraterrestrial creature is hunting down residents - and that he is the next target.