Captain Picard is contacted by three other Starfleet captains who give him some disturbing information.
This is an intriguing and gripping episode with number of memorable scenes and character moments.
The plot for me is reminiscent of the original series episode 'Operation Annihilate', only better as it presents the possibility of Starfleet's command structure being compromised by an alien organism.
What works well is that right from the moment Picard is woken from his slumber there is an established sense of dread that remains until the end credits. It all stems from some quite atmospheric early scenes that set the tone for the rest of the episode. For what feels like the first time in the series we are faced with a credible threat.
Several characters make a strong contribution to the plot. It centres around Picard who leads from the front, placing himself in peril in the line of duty. Riker, Data and Dr Crusher all support him well and display the strengths unique to their characters.
The visuals are a mixed bag in terms of quality, but they entertain nonetheless. The scenes on Dytallix B are well designed, filmed and set the tone well. The creature effects are easily identified as clay animation but if you keep in mind this is 80s sci-fi you should appreciate the effort gone into making them as cinematic as possible. At one point it feels like a horror movie due to the comparatively graphic nature of the models.
All performances are strong with Patrick Stewart carrying the story superbly well. Jonathan Frakes, Brent Spiner, Gates McFadden are all solid. Ward Costello and Robert Schenkkan return with memorable performances.
The only real problem with this episode is that the story is never followed up at any point later in the show. However, judged on its merit it is for me the strongest of the first season.