Operation -- Annihilate!

Parasitic flat fish will send you insane, once they've made it inside you're as good as slain, it's a fight to discover, a remedy to recover, from psychosis inducing such pain.

The population of the Deneva colony come under attack from a space borne parasite that subsequently kills all while putting its host under extreme physical and mental torture.

The Enterprise is going to investigate what appears to be a very slow-moving viral form of mass-hysteria which has, over centuries, brought several thriving civilizations on many different planets down. Spock reviews the epidemiology of the phenomenon at the beginning of the episode, revealing that the trajectory of the epidemic places a Federation colony directly in its path. Sam Kirk, his wife and their son, live in this colony.

Captain Kirk is directly affected by his family's involvement in all of this, and Shatner does a very nice job of portraying a captain whose professionalism and rational judgment are threatened, and whose usual rational support structure (Spock) is also imperiled and unavailable. In a scene which was, unfortunately underexploited by the mediocre script, Dr. McCoy rises to the occasion and, surprisingly, fills both his usual role and that of the great first officer.

Herschel Daugherty directs this memorable episode of TOS, and does an admirable job with a somewhat weak script. The Stephen Carabatsos script creates some problems for the acting (particularly Nimoy, Barrett and Kelley), and - like his previous effort "Court Martial" - makes the pace a bit inconsistent. Kelley and Shatner are truly remarkable despite these challenges.

The episode also uses setting very nicely, with a very minimal use of backdrops and carefully chosen locations for rare open air shots. Additionally, Spock's character is very nicely examined, the developing rivalry and friendship between McCoy and Spock is enhanced, and the powerful - though unresolved - relationship between Christine Chapel and Spock begins. Finally, this (and the great earlier City on the Edge of Forever)is one of the first episodes to exploit the (unfortunately largely overlooked and unrecognized) subtlety of William Shatner's acting ability by placing Kirk's personal life in the way of his professional practice. This became a major theme as the series continued into its 2nd and 3rd seasons.

If anyone doesn't see the similarities to RA Heinlein's Puppet Masters, well, I don't know what to say.

Enterprise visits Deneva where colonists are inexplicably becoming violent and destructive.

I enjoyed this episode for the sci-fi concept and the performances of the central characters.

It starts off intriguing and dramatic as something very strange starts to happen and there is a family connection to Kirk. From there the plot unfolds quite compellingly and there is an interesting focus on both leadership, scientific research and Spock's Vulcan physiology.

I love the idea for the single-cell creature and the connection to a host. All the science associated with this works very well for me. Another reviewer has mentioned the Cold War allegory which is good, but for me is not quite as deep as it probably tries to be.

Kirk, Spock and McCoy take centre stage in a riveting battle against an unusual enemy. This for me is a classic example of Star Trek science and logic winning the day. However, it is a bit contrived for one character to save the day when it would be more plausible that one of the other two would have provided the solution given their scientific roles. Another huge contrivance comes at the very end which by today's standards of TV show storytelling is rather poor.

The visuals are a mixed bag as the location does not look anything other than the complex in Southern California where it was filmed. However I like the creature effects, which are very simple but work well.

Performances are mostly great with William Shatner, Leonard Nimoy and DeForest Kelley all on good form, particularly Nimoy. Some of the guest actors are not so great, especially Joan Swift who is comically over the top.

For me it is a 7.5/10.

The Starship Enterprise arrives at the Planet Deneva where Captain James T. Kirk is looking forward to a little personal time with his brother Sam and Sam's wife and son. But it turns out the planet and its people are under attack by some strange collective parasite intelligence which attachs itself to people and forces them to their will under duress of great pain if they don't.

William Shatner's brother died from it and his sister-in-law and nephew are still in its grip. Also Leonard Nimoy is attacked by one of the parasites himself and functions under great pain.

It's a medical problem that DeForest Kelley diagnoses. But surgery is too complex and to have a whole planet undergo it is time consuming and not terribly efficient.

Nimoy proves a useful guinea pig for an experiment that Kelley conducts as to the cure which I won't reveal. But the risk might be genocide on a planetary scale and Kirk is truly reluctant to take that on as a responsibility.

Another episode involving the strain of command and the choices a commander might have to make. These parasites apparently have been making their way through space and it's a question of preventing this from spreading to places like Vulcan and Earth.

Shatner handles it well and Kelley is a good doctor.