Crew members beam down to a beautiful planet, where they slowly realize that their thoughts are magically manifested into reality. After a number of apparent misfortunes, the crew learns the world they're on is a magical alien amusement park, capable of making dreams come true.
"Shore Leave" isn't a wonderful story, but it does have an undeniable sense of fun. Kirk is beat up by his academy-days tormentor, and later gets to return the favor (it's fitting for the captain that his idea of fun is having the chance to "beat the tar out of Finnegan"); Sulu gets to fire off a few rounds with a six-shooter; and Bones gets to chase a white rabbit, then die, and then come back to life. This episode maintains enough balance between adventure, danger, comedy, and silliness that it manages to be a pleasant hour of rather non-cerebral fantasy.