Complex sentence: Unfortunately, when Wrongway returns to civilization, he is unable to tell anyone where the Castaways are, owing to his poor sense of direction and the story about the Castaways is written off as another one of his fanciful tales.
Split into simpler sentences: Unfortunately, when Wrongway returns to civilization, he is unable to tell anyone where the Castaways are, owing to his poor sense of direction. The story about the Castaways is written off as another one of his fanciful tales.