The Shadow World — Jane Johnson

Ben Arnold had hoped that exposing Mr. Dodds's vile Pet Emporium -- a business that stole magical creatures from Eidolon to sell to England's rich and curious -- would prevent the Secret Country from fading away into ruin. However, it soon becomes clear that the evil, dog-headed Dolman's reign of terror has only just begun.

Ben's mother, Queen Isadora, returns to her homeland to lead its creatures against the Dodman. Unwilling to be left behind, Ben's sister, Ellie, crosses into the Secret Country and walks straight into a trap. Ben and his father follow close behind, and soon the entire Arnold family is scattered across Eidolon's magical and dangerous terrain. The Arnold children are destined to save the Secret Country, but first they must save each other.