Zak, Nick and Aaron answer the call to help homeowners understand the horrors that have plagued them inside their haunted, century-old, Victorian mansion. Lillian Otero and Edwin Gonzalez bought their "dream house" in 2009, but the paranormal events were so overwhelming that they eventually had to move out. The guys are determined to communicate with these relentless spirits to better understand why they keep haunting Edwin and Lillian.

For their 100th episode, Zak, Nick and Aaron visit St. Louis to investigate the notorious Exorcist House, the site of the most famous possession in paranormal history, which was later portrayed in a critically acclaimed book and movie. The guys dig even deeper to learn about the original exorcism that occurred on March 16, 1949.