Following the violent explosion of an energy production facility on the Klingon moon of Praxis, the collapse of the Klingon Empire is considered imminent. In 2293, the United Federation of Planets decides that this is the opportunity to finally negotiate a true, lasting peace with the Klingons. Chancellor Gorkon, the leader of the Klingon High Council, immediately heads towards Federation space for the proposed peace conference.

Captain Spock suggests that the U.S.S. Enterprise be Gorkon's escort, forcing Kirk, who still harbors deep resentment for the brutal death of his son at the hands of the Klingons, to meet the Chancellor's ship. The two ships rendezvous peacefully and are proceeding towards the conference when the U.S.S. Enterprise suddenly appears to fire on the Klingon ship and Federation-uniformed men beam to the ship and mortally wound Gorkon. After beaming over to the Klingon ship with Kirk to lend assistance, Dr. McCoy is unable to save Gorkon's life. McCoy is arrested, along with Kirk, for the murder. After a quick trial before the Klingon High Council, the two men are sentenced to imprisonment on a Klingon penal colony. Unknown to the Klingons, however, is that prior to Kirk's beam-out from the Enterprise, a quick-thinking Spock surreptitiously attached a homing patch to the back of Kirk's uniform.