Rescued from the horrors of an animal research laboratory, the mastiff, Garth, discovers that his new freedom comes with certain obligations. Released into a new world where the Grey Men have gifted the Canidae the power of speech and higher consciousness, he persuades the rest of his adoptive pack that they must help the aliens complete their mission to 'unmake' the human species. In the course of doing this Garth discovers much about the true nature of his relationship with the Grey Men, including that his own future is not as liberated as he first imagined.

On Garth's journey of discovery, he is accompanied by a colourful assortment of canine companions, whose adventures celebrate the richness of personalities in the canid community, as they struggle to understand the implications of their new capabilities. One major difference between them and the humans becomes starkly evident by the end of this remarkable tale.