Regarding all episodes:
I love this six-part adventure because each episode is an own story and has something really special. The change of the locations (from an island in an acid sea and a screaming jungle to an ice world and a futuristic city) is brilliant and the story overall about the five keys of Marinus is truly well-written. In my opinion, "The Keys of Marinus" is an underrated masterpiece!
Review of The Keys of Marinus
