Sally and Jimmy are twins living with their parents in the most boring suburban street in the world but on their 12th birthday an accident and subsequent medical treatment reveal that Sally is an alien. Her twin brother Jimmy is human but she is not. For a thousand years a space war has been raging between a Galactic Empire and Ursoid invaders and Sally, an Imperial princess, was implanted in the womb of a human mother in order to hide her from her Ursoid enemies. The night the twins were born, an old lady named Mrs Webster moved into the house next door and ever since she has given the twins cookies, milk and lessons in military strategy. Now Sally’s secret is out, her Ursoid enemies are coming for her and the twins and Mrs Webster, now revealed as an undercover Master Sergeant in the Imperial Marines, tasked to be Sally’ bodyguard, have to keep her alive until help arrives from the Galactic Empire.