Charles and Lizzie Peterson love puppies. Their family fosters these young dogs, giving them love and proper care, until they can find the perfect forever home.

After getting home from school, Lizzie is surprised to hear that her parents are fostering another yorkie puppy. After all, their last yorkie foster, Princess, was a little spoiled. But Biggie is Princess's total opposite: He's energetic and tenacious! Can Lizzie find this teeny puppy with a big heart a perfect home?