Complex sentence: Leigh soon falls through the attic floor, and after a brawl between Kelli and Agnes, knocking over some candles and starting a fire, Billy also makes his way into the attic, and Agnes and Kelli both fall in between the walls.
Split into simpler sentences: Leigh soon falls through the attic floor, and after a brawl between Kelli and Agnes, they knock over some candles starting a fire. Billy makes his way into the attic, and Agnes and Kelli both fall in between the walls.