In 2267, she was assigned to a mission to Epsilon Canaris III in order to prevent the outbreak of war. Her mission was cut short when she contracted Sakuro's Disease, and the USS Enterprise was sent to transport her to a medical facility. The shuttlecraft sent to bring Hedford to the ship, however, was seized by an energy-based alien entity and diverted to Gamma Canaris N, an uncharted planetoid in the Gamma Canaris region. There, Hedford and the Enterprise crew encountered Zefram Cochrane, who had gone missing from Alpha Centauri 150 years earlier.
Hedford's medical condition worsened while grounded on the planetoid. Just before succumbing, Hedford agreed to merge with the alien, known as The Companion, who loved Cochrane but was unable to be loved by him in its alien form. Hedford and Cochrane planned to live out the remainder of their normal lifespans on the planetoid. (TOS episode & Star Trek 7 novelization: Metamorphosis)
According to Captain James T. Kirk's official log, Hedford died in May 2267 while aboard the Galileo shuttle. He fulfilled his promise to Cochrane and Hedford that he would not tell Starfleet about them. (ST reference: StarTrek.com)
Doctor Leonard McCoy filed her certificate of death. However, Kirk had recorded the truth of what had happened in his personal log, which he expected to remain sealed for 100 years. (TOS novel: Federation)
Later in 2267, five experimental Federation starships disappeared while testing hyperwarp propulsion. Seeking guidance from the foremost expert on warp drive, Kirk, Spock and McCoy returned to Gamma Canaris N. The Companion separated from Nancy Hedford's body in order to take the Enterprise into the starless universe where her species originated. During this time, Hedford survived on her own for several hours, unconscious, but would have perished if The Companion had not returned in time. (TOS comic: "A Warp in Space")
In November 2267, Kirk was brought to task after Starfleet Command received a distress call from Hedford. The Enterprise returned to Gamma Canaris N to find Cochrane missing and Hedford/Companion suffering from hypothermia and injuries from a weapon discharge. Hedford/Companion sensed where Cochrane had been taken and determined that they could survive away from the planetoid for six days. She left with the Enterprise to rescue him, eventually winding up together aboard a shuttle within a black hole disruption.
In May, 2366, temporal distortion brought Cochrane and Hedford/Companion ahead in time. They were recovered by the USS Enterprise-D. However, Gamma Canaris N had collapsed to debris nearly a century earlier without The Companion's presence, and Cochrane had been mortally wounded. Cochrane and Hedford/Companion died together in the Gamma Canaris region aboard the Enterprise-D. (ST novel: Federation)
In one alternate timeline, Hedford was a junior administrator assigned to Epsilon Canaris III in 2259, where her creative negotiations were able to keep the planet's society from collapsing. Over the following years she became a successful diplomat, and in 2264, as an ambassador, she headed the mission to have United Earth join the Coalition of Planets. (Star Trek: Myriad Universes novel: A Less Perfect Union)
- Hedford's height and weight are those of Elinor Donahue, the actor who played her. (Elinor Donahue's biography)
- TOS episode & Star Trek 7 novelization: Metamorphosis
- TOS comic: "A Warp in Space"
- ST novel: Federation
- Star Trek: Myriad Universes novel: A Less Perfect Union