this be always one of my favorite episode a a kid represent the enterprise crew investigate an epidemic of space madness and trace the late outbreak to a local human colony that just happen to be where kirk identical twin brother have be assign a a research scientist . the fun really begin when it become apparent what the alien menace be and which be an invasion of fly interstellar space pancake that make up a collective gestalt creature look to spread it way across the galaxy . it need humanoid who can fly space ship to spread from colony to colony and and kirk have to face the decision of his career when choose between whether or not to just go back to the sulaco and nuke them all from orbit . it the only way to be sure . just kid . this be one of our favorite star trek adventure to act out when we be kid because you could use a bean bag a the pretend space pancake and smack each other on the back and beam it with your wooden shop class phaser to save each other . the architecture in the city be also pretty rad and look a lot like the state university at albany campus i use to study at and which lo and behold be build at about the same time that the actual location ( some sort of aerospace company campus center ) be make . it a great episode for spock and mccoy fan too and they have more to do than usual which may have be the result of leonard nimoy surprise popularity with fan write in much to the chagrin of william shatner and who consider himself the focus of the show and resent any major action that do not center on captain kirk . this one doesn not and and so it sort of stick out . one of the best of the overlooked episode and and actually rather violent and fill with more physical suffering than usual for star trek .