In the mid-21st century, dogs are all but extinct. An experiment gone awry caused every canine on Earth to become hyperintelligent. When as a species they stopped wagging their tails, hysteria ensued—followed by a program of mass euthanasia. Now the only surviving dogs are relegated to a sanctuary off the coast of Florida: Dog Island. There, they are studied in a wild, feral, and protected state. And there, too, their robot replacements are tested before being sold for mass consumption.
Seventeen-year-old Nano Miller was born and bred on Dog Island, as were her two best friends, Jack and Wolf. Life has been mostly wonderful except for annual heartbreak, when another robot dog is torn from her arms and replaced with the latest model. And more recently, there is the heartbreak of her brother, Billy, who vanished without a trace a year earlier. Wolf, there to console Nano, has suddenly become more than a friend. (Bad news for Jack.) With the excitement of a surprise first romance, Nano is happier than ever, in spite of her loss. But then she makes a discovery that upends everything she took for granted: a living puppy who wags its tail. And there is no way she is letting this dog go.