These houses have a secret. Wanna know what it is? They've all got secret spaces ... skillfully-engineered, carefully-constructed hidden passageways, rooms and yes ... even dungeons! We've crisscrossed the country to get an up close look at what homes across America are hiding and show how they were designed, built and installed. From invisible bathrooms, bedrooms and playrooms to a secret laboratory fit for a Munster, they're amazing mind-bending secret spaces!