Puppy rescue riddle

A storm is coming to coastal North Carolina. Amy and Elliott - volunteers at the local dog shelter - have a job to do. The rescued puppies need to get to higher ground, and fast! The kids scramble to get the puppies into their cages, and then the van of volunteers and dogs is on its way. But they are one puppy short. Did it run off in the rain? Is it back at the shelter? An old book, a series of riddles, and a spooky storm all lead to a mystery only the kids can solve.