Complex sentence: The rest of the girls have been locked in the gruesome dungeon by the evil Lord Throckmorton and the knights that took care of them were chained and starved, as Cecilia find out later in the book.
Split into simpler sentences: The rest of the girls have been locked in the gruesome dungeon by the evil Lord Throckmorton. The knights that took care of those girls were chained and starved, as Cecilia find out later in the book.