During a bust the boys are introduced to the Master of Shadows, a very powerful ghost controlling the ones being busted. He introduces himself to Egon and commends his intelligence, when the rest of the boys try and capture him he escapes telling them that he will set the city ablaze and it will be their fault it occurs. In order to stop this Egon uses his latest invention to speak with the Master of Shadows. After managing to force a meeting for midnight that night, Slimer manages to damage the machine switching his body and Egon's.