When Tory Brennan's mother dies suddenly she is sent to live with the father she has never met on a remote island in South Carolina. Tory might find getting to know her dad difficult, but she has no trouble making friends with the island's other teenage inhabitants: Shelton, Hi and Ben. They quickly form their own gang, united against the snobby pupils of the posh high school they all attend.
Things change dramatically for them, though, when they rescue a sick wolf dog puppy who they find locked in a secret cage in a research laboratory. The four nurse him through his illness, in their bunker hideout, until he is better. But it's not long before they all fall sick. Could their illness have something to do with the puppy? And what does the head of the laboratory have to hide?
Sneaking back onto the island to try to find out what's going on the four are shocked to discover some long-buried human bones. But before they can dig them out, they are shot at and chased off the island. Fleeing for their lives, something strange starts to happen. Suddenly Tory feels she could run all night. Shelton sees more sharply; He can smell odours he's never noticed before. And Ben's eyes have changed colour.
Alarmed by the change in each other, they retreat to their bunker. It's clear they have become involved in something fatally dangerous. And if they don't find out what's going on soon, they could end up like the poor person buried on the island.
And what on earth is this strange change in them all about? Could they possibly have developed canine powers? They soon realise that if they can harness their powers, it just might save their lives.