Owen Baker is a 12-year-old loner who has been working as a neighborhood dog-walker so he can earn the privilege of getting a dog of his own. His hard work pays off when his parents let him adopt a scruffy mutt he names Hubble. Both boy and dog get more than they bargained for when Owen wakes up one morning to discover he can understand every word Hubble says, including the ominous phrase: "Take me to your leaders." Owen learns that dogs came to Earth thousands of years ago to colonize and dominate the planet. Hubble (who is really named Canid 3942) has been sent by the powerful Greater Dane on a mission from the Dog Star Sirius to make sure dogs have fulfilled this destiny. Despite the best efforts of Owen's rag-tag group of neighborhood dogs to convince him otherwise, Hubble soon discovers the awful truth about Earth dogs: "You're all pets!" Now Owen (a boy who never had a friend) and Hubble (a dog who never needed one) must work together to prepare the neighborhood dogs for a visit from The Greater Dane--or all dogs will be removed from the planet! The fate of Earth dogs hangs in the balance, and it's up to Owen, Hubble, and their canine companions to save man's best friend. 我们都是好孩子。。不养狗狗很多年。狗狗长得略丑了点。。。。 小男孩欧文（连姆·艾肯 Liam Aiken 饰）辛辛苦苦的工作了一整个夏天，父母终于同意了他在家里养宠物的请求，就这样，欧文将一条名为哈勃的狗狗迎回了家。有哈勃陪伴的生活每一天里都充满了新奇和快乐，然而，随着时间的推移，哈勃逐渐展现出了和一般狗狗大相径庭的特质，让欧文对哈勃的真实身份起了疑心。 原来，哈勃并不是一只普通的狗，它来自于遥远的“狗星”，是一条名副其实的“外形狗”。狗星的首领一只企图侵略地球抢夺人类的资源，因此派出了很多间谍前往地球，潜伏在人类的身边。可是，让它百思不得其解的是，这些间谍们在来到地球之后很快就纷纷音信全无，于是它派出了哈勃，狗星上最精明强干的特工前往地球一探究竟。
