Wolf in the Fold
Scotty is believed to have murdered a young dancer on a planet bereft of violence. Through course of investigation, the real threat is found to be a force from Earth's past that feeds on fear.
An uneven episode in tone: is it mystery, drama, comedy, horror? A strong case could be made for the latter, as many horror clichés pop up, from séance to demon possession. Not a positive trend for the series. Any hopes for development for Scotty are dashed, since we learn only that he's an old Aberdeen pub-crawler and not a murderer. (And these things we could probably figure out anyway.) The inhabitants of Argelius II aren't too interesting, and Hengist is really obviously the bad guy. Since the "mystery" is easily solved - at least as to which humanoid dunnit - and the murders predictable (hmm, let's send the murder suspect into a locked room alone with a young female officer) this becomes courtroom drama. The trial, however, also becomes tiresome, until Redjac's true nature is discovered. Then: fun with sedatives! Good lines from Sulu and McCoy. Still, I'm not sure a giggle fest is the best way to end a tense mystery-drama. A similar shift in tones is seen in Day of the Dove, but is logical and beneficial there. This one's just confusing, wasting a decent "truth behind the old earth phenomenon" premise.
Spock Saves the Day: Spock probes the computer to find Redjac's identity and helps fight those it inhabits.
Oops: Spock is absent for most of the show, so no blunders.
Developments: Clearly stoic Spock is going to avoid a hedonism planet, and only becomes involved with its people when proceedings become deadly. Nor is it surprising he opts out of the sedative treatment. Such substances can have dire effects on Vulcans and their reputations.