Forced to live a segregated life, the aliens live behind a huge wall in a ghetto called Troy. Border guard Lewis's life is thrown into turmoil after an encounter with mysterious alien Lilyhot, when he discovers he is actually half alien himself, and things spiral out of control when his sister Holly becomes embroiled with an alien drug gang and is kidnapped and taken into Troy. With the help of alien cleaner Dominic, Lewis is forced to find a way to save his sister.