Dr. Elizabeth Dehner
Lieutenant Lee Kelso
on a mission to gather data about the force field which surrounds the
galaxy, the Enterprise intercepts a distress signal from the flight recorder
of S.S. Valiant which had also come across the force field two hundred
years previously and had since been listed as missing.
On analysing the memory banks of the recorder, Spock notes many requests
for information on E.S.P. ( extra-sensory perception ) and hears the captain
of the Valiant ordering the self-destruction of his vessel.
The Enterprise also tries, unsuccessfully, to breach the barrier, resulting
in the deaths of nine crewmembers and serious injuries to psychiatrist
Dr. Elizabeth Dehner and Lt. Commander Gary Mitchell. As they recover,
Mitchell and Dehner start to display an ability to control objects with
their minds, including the controls of the Enterprise.
The ship's surgeon, Dr. Piper, believes that they are rapidly evolving
into a new form of human at a fantastic rate and, realising the threat
to the Enterprise, Spock recommends that they be transported down to a
deserted Lithium cracking facility on the planet Delta Vega.
Kirk disagrees at first, as Gary Mitchell is an old Starfleet Academy
friend, but is forced into the situation when Mitchell murders a crewmember
while escaping from shipboard confinement. Captain Kirk and Dr. Dehner,
who is apparently less affected, follow Mitchell down to the planet to
try and reason with him but the changes have progressed too far.
He tries to kill Kirk, who is partly protected by the limited powers of
Dehner, and in the ensuing battle both mutants are eventually killed.
James Kirk, in memory of the friend that he once knew, logs both deaths
as being the result of the performance of their duties.