The Virtual Storyteller is a Multi Agent System (MAS) that can generate stories by simulating a virtual world in which Character Agents pursue their goals. The claim is made that the story emerges from the events in the virtual world. The goal of this project has been to make the stories more interesting. This thesis describes how to extend the Virtual Storyteller with a Plot Agent that will direct the events to generate more interesting stories. For this, three research questions have been tackled. Firstly, the system needed a better understanding of the emerging story. For this, a fabula structure has been designed that captures causality between story elements such as emotions, goals, actions, events and perceptions. A plot within the fabula revolves around a single goal and contains everything that is affiliated to that goal. Secondly, plot control techniques have been explored where attention has been paid to the fact that believable characters should be kept autonomous. Four ways to influence the story are: (1) generating events to mediate the plans of characters, (2) influencing their perceptions, (3) changing the setting, (4) suggesting goals or actions. Thirdly, an exploration has been made as to what decisions the Plot Agent needs to make to direct the story, and to aid these decisions, a creative problem solver has been designed that uses case based reasoning to solve problems.