Complex sentence: The Great Unknown is a fictional entity in the book series "A Series of Unfortunate Events" by Lemony Snicket, it features in the 11th ("The Grim Grotto ") and final ("The End") books of the series.
Split into simpler sentences: The Great Unknown is a fictional entity in the book series "A Series of Unfortunate Events" by Lemony Snicket. It features in the 11th ("The Grim Grotto ") and final ("The End") books of the series.