The treehouse is found near the Morgans' House. Derek Morgan uses it as a hideout, where he can stay if his father gets mad at him. In the hideout, he has various pictures of his dad drawn in crayon, all portraying him in a negative light. He also has a plan to kill his father, involving putting rat poison in his beer. This was Plan A, implying that he either has more hidden somewhere, or he plans on making more.