From the moment she arrives in the Florida Keys, twelve-year-old Carly knows she’s found her true home.

She loves everything about the place, from the gaudy sunsets to the shimmering water of Florida Bay. Because she’s new to the Keys, though, she doesn’t know it’s against the law to feed the wild dolphin she discovers when she paddles her kayak to a mangrove island near her house. You’ll make him dependent, a local vet warns her. You’ll make him vulnerable.

When the dolphin gets sick, Carly feels terrible. She reaches out for help, first to her friend Fin, a twelve-year-old conch who knows everything about the local waters. Fin gets the neighborhood grandmas involved, and they draw in their friend, a marine mammal vet. As Carly assembles her team, the first clue appears — a strange odor in the water at a nearby campground. Using all her sleuthing powers, Carly struggles to track down the evil polluters and stop them. Along the way, though, she realizes the dolphin she loves doesn’t really belong to her. He’s a wild creature, after all, and he needs to be free.