Spock and Joe Tormolen beam
down to planet Psi 2000 to pick up a research party before the planet
disintegrates. They find everyone has died, frozen when life support
was turned off. Even stranger, the positions of the researcher's bodies
show they were out of their minds when they perished and some died by
Tormolen carried what is later termed the "Psi 2000" virus, back to the
U.S.S. Enterprise and it spreads among the crew at an alarming rate,
reaching into their souls and pulling out their deepest desires for
public display. The virus is water borne and spread by perspiration in
a touch. While trying to stop Tormolen from killing himself, Sulu and
Kevin Riley are infected with the virus.
crew begin displaying actions that are humorous exaggerations of their
desires, like Sulu threatening the bridge with a fencing foil and Kirk
becoming overly romantic toward the crew. Others are more
heart-wrenching, like Christine Chapel admitting her love for Spock and
the Vulcan finally weeping over his mother's death. The deadliest
result, however, is when Riley
declares himself captain of the U.S.S. Enterprise and locks himself in
Engineering. Unfortunately, he also locks everyone else out. Once in
command of the ship's engines, Riley shuts them down and the U.S.S.
is pulled toward Psi 2000 by its erratic gravity.
finds an antidote for the virus which he, fortunately, manages to
avoid coming down with, and infects the crew.