Twelve-year-old Owen has been working as a dog-walker all summer, and his hard work has finally paid off - he gets to adopt a dog of his own! But Owen gets more than puppy love when he discovers his new dog, Hubble is actually an interplanetary scout from the Dog Star Sirius. Owen must help Hubble train a group of undisciplined neighborhood dogs to shape up for a visit from their leader, the powerful Greater Dane - and the fate of all Earth dogs hangs in the balance.