Complex sentence: Teddy takes Tilly to the schoolhouse, where Tilly begins to remember the events surrounding Stewart Pettyman's death, Stewart subdued her against a wall, threatening to come at night to murder her mother and assault her if she moved.
Split into simpler sentences: Teddy takes Tilly to the schoolhouse, where Tilly begins to remember the events surrounding Stewart Pettyman's death. Stewart had subdued her against a wall, threatening to come at night to murder her mother and assault her if she moved.