The local humane society is hosting a puppy adoption day on the Shiver-by-the-Sea town common, and Bella Gossi, her friend, Cooper, and his basset hound, Casper go to check out the dogs. Bella's immediately drawn to a shy, scruffy, scraggly puppy at the far edge of the pen. When every other puppy gets adopted, Bella, feeling sorry for the little pup, agrees to foster her over the weekend while the shelter figures out what to do with her.

But when the sun goes down, the sleepy, scruffy pup goes positively wild in Uncle Van's house--racing around, chewing everything she can get her teeth on, and howling at the moon. Can Bella figure out what's up with the pup before some unsuspecting family takes her home?