I know that in my M:I book, there are quite a few episodes that were made simply by someone walking up to the producers and pitching a one or two sentence description of the set up.
A couple of episodes were built around devices/equipment someone had seen at a lab and they went back to the producers and said, "Wouldn't it be great if we could build an episode around this device?"
The producers would then give that idea to the script editor who would work in conjunction with the individual who pitched the idea in order to flesh out the story and the beats.
A couple of episodes were built around devices/equipment someone had seen at a lab and they went back to the producers and said, "Wouldn't it be great if we could build an episode around this device?"
The producers would then give that idea to the script editor who would work in conjunction with the individual who pitched the idea in order to flesh out the story and the beats.