Plot outline

When the U.S.S. Enterprise

USS Enterprise (NCC-1701)

The USS Enterprise, NCC-1701, is a fictional starship in the Star Trek media franchise. The original Star Trek series depicts her crew's mission "to explore strange new worlds; to seek out new life and new civilizations; to boldly go where no man has gone before" under the command of Captain James...

 visits the planet Dramia to deliver medical supplies, the authorities immediately arrest Dr. McCoy for mass murder. The Dramians allege that 19 years prior Dr. McCoy had supervised an inoculation program against Saurian virus on Dramia II, and that once he had left most of the inhabitants died from a plague.

Kirk takes the Enterprise to Dramia II to investigate, and in the process the crew gets infected with the same plague.