Thunder loves her life by Sage’s side -- together, they make the paw-fect pack! But when Sage invites a foster dog named Byron into their den, suddenly things get a lot more complicated. Byron doesn’t seem to know the pack rules—he's sleeping in Thunder's bed, eating out of her bowl, playing with her toys, and is even stealing love from her human!

Will Thunder find a way to get along with this unwelcome guest? And can she maybe, just maybe, call him friend?

For fans of PAWS and KATIE THE CATSITTER, and anyone who has ever pondered the secret life of their four-legged sidekick, join Thunder and Sage on their newest adventure — and get ready to feel ALL THE WAGS!