In an age of so many streaming options it can sometimes be paradoxically difficult to find something good to watch. If you’re looking for quality documentaries based on the history of espionage then there are a surprising number of excellent, free choices for Amazon Prime subscribers.

During WWII, British technicians and engineers developed an incredible variety of weapons and gadgets at Station IX located on the grounds of the Frythe Estate near Welwyn, England. Here are five of the unique weapons they developed for use behind enemy lines.