This was always one of my favorite episodes as a kid: The Enterprise crew investigates an epidemic of "space madness" and traces the latest outbreak to a local human colony that just happens to be where Kirk's identical twin brother has been assigned as a research scientist. The fun really begins when it becomes apparent what the alien menace is, which are an invasion of flying interstellar space pancakes that make up a collective gestalt creature looking to spread it's way across the galaxy. It needs humanoids who can fly space ships to spread from colony to colony, and Kirk has to face the decision of his career when choosing between whether or not to just go back to the Sulaco and nuke them all from orbit. It's the only way to be sure ...<br /><br />Just kidding. This was one of our favorite Star Trek adventures to act out when we were kids because you could use a bean bag as the pretend space pancake and smack each other on the back, beaming it with your wooden shop class phaser to save each other. The architecture in the city is also pretty rad, looks a lot like the State University at Albany campus I used to study at, which lo and behold was built at about the same time that the actual location (some sort of aerospace company's campus center) was made. It's a great episode for Spock and McCoy fans too, they have more to do than usual which may have been the result of Leonard Nimoy's surprise popularity with fans writing in -- much to the chagrin of William Shatner, who considered himself the focus of the show and resented any major actions that didn't center on Captain Kirk.<br /><br />This one doesn't, and so it sort of sticks out. One of the best of the "overlooked episodes", and actually rather violent & filled with more physical suffering than usual for Star Trek.