Complex sentence: That night, Clark accidentally falls into the room's fireplace when trying to recover Lois' fallen hairbrush; when Lois discovers his hand is unburned, Clark is forced to admit he is Superman.
Split into simpler sentences: That night, Clark accidentally falls into the room's fireplace, when trying to recover Lois' fallen hairbrush. When Lois discovers that his hand is unburned, Clark is forced to admit he is Superman.