When the Enterprise visits Dramia to deliver medical supplies, the authorities arrest
Dr. McCoy for mass murder. They contend that 19 years earlier McCoy had supervised an
inoculation program 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 the crew gets infected
with the same plague.
Spock invokes Starfleet General Order #6 when the entire Enterprise crew except himself has been stricken with the deadly Dramian plague. According to Helmsman Sulu, the order is, "If everyone onboard has perished at the end of 24 hours, the ship will self-destruct in order to protect other beings from the disease onboard."