Some years before this
second pilot, the S.S. Valiant had encountered a unknown energy barrier
at the rim of the galaxy. Something had then made its captain destroy
Enterprise finds the Valiant's
disaster record-marker, which reveals that just prior to its
destruction the crew had been searching library tapes for any
information on psionics.
Enterprise arrives at the edge of the galaxy and the same force affects
the ship's drives that must have affected those of the Valiant. Kirk
notices a strong personality change in his good friend, Lieutenant Gary
whose latent psionic abilities are heightened by the force field. Soon
Mitchell has gained enormous extrasensory powers, displaying many
talents which include moving objects with his mind and controlling his
own heart rate. To a smaller degree, Dr. Elizabeth Dehner is also
affected by the force field's power and the two are drawn together by
their common powers.
powers grow, he becomes more dangerous. Spock believes that when the
the same phenomena, it destroyed itself to prevent the power from
taking over the galaxy. Gary Mitchell confirms his fears when he
informs them that he is becoming a god who will rule the humans. Spock
feels that Mitchell's death is the only solution, but Kirk is unable to
kill his old friend. Instead, he exiles him to an uninhabited planet.
However, once on the planet's surface, Mitchell kills his guard and
escapes, taking Dr. Dehner with him. Kirk follows with a phaser rifle
and Mitchell attempts to kill Kirk with his psionic powers.
this display, Dr. Dehner realizes how inhuman and dangerous Mitchell
has become and tries to help Kirk defeat him. Without remorse, Mitchell
kills Elizabeth Dehner. Before he can refocus his psi powers, Kirk
creates a rockslide that entombs Mitchell, killing him.
admits to Kirk that for the first time in his life, he felt something
akin to human emotion.