The Enterprise is sent to investigate the disruption of the Gamma VII-A solar system and the destruction of the U.S.S. Intrepid, staffed solely by Vulcans. When they arrive they find a large dark mass floating in space that is draining energy from everything around it, including the Enterprise. Drawn into the mass, they find a huge amoeba-like creature and Kirk must decide which of his two friends, McCoy or Spock, to send into it aboard a shuttle craft on a mission of no return. Written by
Did You Know?
The young crew woman whom Kirk admires as he records his log at the end of this show appears to be the same extra who portrayed the other female Klingon seen in "Day of the Dove". See more
At one point during Kirk, Spock, and McCoy's discussion of using a shuttle craft to determine how to destroy the organism, McCoy crosses over so that he is next to Spock, but the cuts between them show the same exact background, even though they are facing each other (This was done this way because there was no wall on the set behind McCoy, from Spock's point of view). See more
Doctor, they seem to be stabilizing.
But at a dangerously low level. Well, we're still alive. I suppose that's something.