Romance is in the air - much to the children's concern - when Thaddeus and Charlotte go off on a book promotional tour together, leaving Peggy, Mike, Laura and Jack in the capable hands of their wacky new nanny - Ruby. The children discover that nearby to their house a boy is being held prisoner and his identity is eventually revealed to be the kidnapped Prince of Baronia. The Prince has been kidnapped by the King's brother who plans to hold the boy ransom and usurp the throne himself.