This is a fantastic episode.
After "The Naked Time", I was really needing it.
The episode (as many, I am observing) has a radical base premise. The Enterprise encounters a boy, Charlie, who grew up completely separated from human interaction. He lacks social tact, but what's more, we discover he possesses unique paranormal abilities. These powers, in the hands of a child-like mind, lead to a great deal of havoc for the crew.
This is the expected aspect. It is pulled off well, and is anchored by a particularly convincing performance by Robert Walker Jr as Charlie. He is the adolescent and is out of place among other humans, let alone space travelers. Whether it's a lesson in butt-slapping from Captain Kirk or a fatherly chastising, it's handled with sincerity and just enough levity. However, it is always the unexpected poignancy that really makes an episode special.
Just as the other challenges Kirk has had to encounter, Charlie reveals another, more layered aspect of his character. What else could I expect, when the plot of the episode makes Kirk's fatherly position to the crew literal. Seeing him deal with the undeveloped mind is a fascinating struggle. His scenes with Charlie are sweet, yet contain an undertone of emotion that heightens the final moment when Kirk nearly looses command of his ship to this boy. These are a great set of sequences that cut right to his core.
Another pearl worth mentioning, is a much more complete version of the Kirk-Spock-McCoy relationship that has only been hinted at in previous episodes. Here it is in full, iconic force. It isn't abrasive, but their thought processes are on display only so far as to pertain to the immediate concerns of the story. It is always a welcomed inclusion when the true nature of a character can be put on display in a fitting manner. Seeing the quibbling of Spock and McCoy rise only to be balanced by Kirk's interjection is brilliant and deservedly classic.
Another note: Uhura's previously hinted attraction to Spock makes a small appearance here in a fun rec-room sequence where she sings to to the Vulcan. Whether or not this was plotted as an intended arc for the two characters or was just an excuse for comedy, I have no idea. In this scene, Spock is seen playing the harp. It seems that this may have been included to hone in on Spock's emotional discipline. Rather than coldness, we see him as calm and reserved. An important distinction that may not have been so clear in earlier episodes.
The storytelling of this episode is tight, wastes no time, and doesn't concern itself with a great deal of fluff. For a ship-based episode to have done as much as it did with character development and suspense is impressive and ambitious.
Stay tuned tomorrow for "Balance of Terror."