Edith Keeler In 1930 , she ran a soup - kitchen out of the Twenty - First Street Mission . Known for her compassion and forward thinking , she sought to bring peace to the entire planet . That same year , she died in an traffic accident . ( ) Alternate timeline . After traveling back in time from the year 2267 through the sentient time portal known as the Guardian of Forever , Doctor Leonard McCoy made the acquaintance of Keeler , who took care of him while he was in a delusional state as the result of an accidental cordrazine overdose . Keeler was a strong and vocal pacifist and her ideas on space travel , new energy sources , and a peaceful society brought ridicule from those at the shelter . Upon recovering , McCoy saved Keeler from dying in a traffic accident , unwittingly changing history . This resulted in the creation of an alternate timeline in which Keeler continued striving for her goals , and eventually founded one of the largest peace movements in the United States . Her actions finally attracted the attention of President Roosevelt , with whom she met on February 23 , 1936 , to confer on her plan of action for assisting the needy . By the late 1930s , the growing pacifism caused by actions Keeler set into motion would delay the United States ' involvement in World War II , allowing Germany to complete its heavy water experiments and be first in the development of the atomic bomb . This , together with the V - 2 rocket , enabled Germany to conquer the world . In the future , Captain James T . Kirk and Commander Spock learned of this alteration to history from the Guardian , who told them that , due to McCoy ' s actions in the past , history had been altered and the Earth they knew no longer existed . Having no choice , Kirk and Spock opted to travel to the past through the Guardian ' s portal , hoping to undo the damage to history caused by McCoy . Arriving at a point in time before McCoy ' s arrival , they made the acquaintance of Keeler , with whom Kirk quickly fell in love and the two began a relationship . Edith also observed that Spock was a true and loyal friend who belonged at Kirk ' s side and that he always would be . Edith mistakenly thought that Spock and Kirk had served together in World War I , and that that was the reason Spock called Kirk " Captain . " Being trapped in the past where money was still used , Kirk and Spock needed clothes and jobs to survive . Spock also needed to acquire electronic components to build a mechanism with which he could retrieve essential information from his tricorder . Edith was able to secure work and living accommodations for both men . Upon reviewing tricorder data taken from the Guardian , Kirk and Spock learned that , in order to restore the timeline , they had to let Keeler die . Reuniting with McCoy , Kirk made the difficult decision of stopping him from saving Keeler from the traffic accident , ensuring her death and thus the restoration of the timeline . ( ) Appendices . Background information . Edith Keeler was played by Joan Collins , and stunt double d by Mary Statler . She was listed as " Sister Edith Keeler " in the end credits of the episode . Apocrypha . In the " " , Kirk was so traumatized by Edith ' s death that he retreated to his family ' s farm in Iowa , where he immersed himself in old letters from his father . In the novel " Battlestations ! " , Kirk named a schooner after Edith . The alternate timeline in which Keeler was saved from death by McCoy was explored in the novel " Provenance of Shadows " . As suggested in the original episode , Keeler ' s influence grew , delaying ( but not preventing ) America ' s entry into World War II .