Eleven-year-old Luke and his dog, Haru, are the best of friends. Luke's parents own a local grocery store in Virginia and live above the store. Luke and Haru go everywhere together, but the landlord, Mrs. Greene, hates animals and hates Haru. One stormy day, Mrs. Greene argues with Luke, and Haru runs out to defend him. She screams and falls, quickly calling the police. Even though Haru didn't bite her, the officers take Haru away. But instead of being put down at the animal shelter, the officers send Haru to a local laboratory. The lab is owned by a multibillionaire, Anton Sinclair, who is determined to find a formula that will keep him alive forever. Sinclair's scientists give Haru an immortality serum that kills him. But what they don't know is that Haru comes back to life, digs himself out of the ground, and heads home to Luke. He has become a zombie dog. Though he acts differently, he is still the same sweet lovable dog he's always been. And though the world is changing and zombie attacks are on the rise, the friendship between Haru and Luke endures, helping to save them all.
