Complex sentence: But things are soon to change for the Peppers when Phronsie is kidnapped by an organ man; a boy a little older than Ben with a big black dog rescues her and comes back to the little brown house to visit her.
Split into simpler sentences: But things are soon to change for the Peppers when Phronsie is kidnapped by an organ man. A boy a little older than Ben with a big black dog rescues her and comes back to the little brown house to visit her.