It's at about this point that the reduced quality of TOS's infamous third season becomes increasingly clear, as what initially appears to be a substantive Spock episode can't even find the right notes. This one focuses on an ambassador named Kollos (performed by a box with lots of blinding light inside) from a race "so ugly as to drive a man mad." Sort of weird, but, okay, I'll grant the story that detail.
Diana Muldaur returns as a guest character named Dr. Jones (that's Miranda, not Indiana), whose life as a human telepath took her to Vulcan, where she learned to control the powers that brought everyone's thoughts into her head. Now she plans to spend her life accompanying Kollos, whom she has come to greatly respect and understand. The problem with the episode is that it's all over the map and never figures out what it wants to say. First the story seems preoccupied with the situation surrounding a character's unrequited love for Miranda, and then his attempt to murder Kollos in a jealous rage and the resulting madness in him that ensues. Then the story shifts when the ship goes wildly off course and only Kollos knows how to get it back on track. This leads Spock to mind meld with Kollos to obtain the information, which leads him to madness.
Subsequently, only Miranda can save Spock's sanity with her mental abilities. The character analysis lies within Jones getting past the fact Spock has communicated with Kollos, with whom she previously shared exclusive mental intimacy. Some of the dialog works, but there's no clear train of thought, resulting in a ponderous mess.