The City On The Edge of Forever - Plot

Plot

Stardate: Unknown. While the USS Enterprise is investigating temporal disturbances from a nearby planet, Lt. Sulu is injured in an explosion. Dr. McCoy gives him a shot of cordrazine and accidentally injects himself with an overdose when the ship is shaken. Delusional, he flees from the bridge and beams down to the planet.

Captain Kirk beams down with a landing party and finds the source of the time distortions, an ancient glowing ring. When an arbitrary question is asked, the "Guardian of Forever" explains that he is a doorway to any time and place. The team locates McCoy, who escapes through the portal. Suddenly the landing party loses contact with the Enterprise and is informed that the past has been altered and the Enterprise no longer exists.

Since the timeline must be repaired, the Guardian lets Kirk and Spock go after McCoy to fix the damage. Kirk tells the rest of the landing party to also try to find new lives in the past if they fail to return. Kirk and Spock arrive in New York City during the 1930s Great Depression. After stealing some clothes to blend in, they meet a woman named Edith Keeler (Joan Collins), who runs the 21st Street Mission. They offer to work for her. Spock begins to construct a processor to interface with his tricorder to find out how McCoy altered history.

Kirk begins to fall in love with Edith. He finds her a remarkable woman. McCoy arrives and stumbles into the mission where Edith takes him in, unbeknownst to Kirk. Spock finishes his work. He finds out that Edith was supposed to have died shortly in a traffic accident but instead she formed a pacifist movement whose influence delayed the entry of the United States into World War II, thus allowing Nazi Germany time to develop an atomic bomb and win the war. Kirk knows that Edith must die to repair the timeline.

Meanwhile, Edith nurses McCoy who tells her his story. Though Edith does not believe him, she tells him that he would like her eccentric new boyfriend.

Later, as Kirk and Edith are walking to the movies, Edith mentions Doctor McCoy. Alarmed, Kirk tells Edith to stay there before running to find Spock. The three friends meet in front of the mission. Edith crosses the street to join them, but is hit by a fast-moving truck. Instinctively, Kirk reacts, but freezes when Spock stops him. McCoy is restrained by Kirk as the truck hits her. McCoy tells Kirk that he could have saved her. “Do you know what you just did?," he says. Spock adds quietly, "He knows, Doctor. He knows."

With Edith's death, history reverts to its original form and they return to the Guardian's planet. The Guardian mentioned that “Many such journeys are possible.” The Enterprise contacts them and the traumatized Kirk responds with the instructions, "Let's get the hell out of here."