Take a look at the tallest doors in the world at the Vehicle Assembly Building at Kennedy Space Center. Visit a company that makes blast doors and bulletproof doors. Learn about the surprisingly complex process involved in making home doors, as well as what goes into those commercial entries and exits we use everyday–the revolving door and the turnstile. At the Southwestern Foundation for Biomedical Research, enter through an airlock into their level 4 biohazard lab. The Cleveland Federal Reserve doesn't even send people into their vaults; its robots go in and out. Try some aviation entries and exits–the jet way used to board a plane, the airplane emergency exit procedures we hope to never use, and ejection seats, the fastest exit anywhere. Then, an engineering firm that designs hidden doors will take viewers to see a few of their secret entries. Finally, take a quick look at doors that go nowhere, at the Winchester Mystery House.