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 final bit of Kirk looking at a crew woman and repeating his line about hoping to "get some rest on some lovely... planet" was not in the script. It was added by William Shatner
and director Joseph Pevney
during filming. See more
When McCoy and Spock leave the bridge after Spock's near-collapse in the opening scene, Kyle, at the helm, is wearing a red shirt. McCoy gives Spock an examination, but does not confine him to Sickbay, so we can surmise that Spock is only off the bridge for a couple of hours at the most. When he returns, Kyle is wearing a gold shirt. See more
Doctor, they seem to be stabilizing.
But at a dangerously low level. Well, we're still alive. I suppose that's something.