When 18-year-old Benjamin Glass goes to look at a dead whale that has washed up on the beach, he meets an unfamiliar dog who follows him home to his caravan. Benjamin isn't equipped to take care of a dog - he has a chronic fear of germs, and is currently living alone while his grandmother is in hospital.

But when a delivery driver recognises the dog as The Mighty Gary, the fastest greyhound in the country, and tells Benjamin about his unsavoury owners, Benjamin is forced to trust the stranger on his doorstep and devise a plan to keep Gary safe.

As Benjamin becomes more attached to the dog, it becomes clear that his trust in the delivery driver may well have been misplaced. He will have to leave his comfort zone, take some unhygienic risks, cross paths with dangerous and powerful men and confront his very worst fears if he has any hope of protecting what he loves the most.