Visit to a Hostile City
"The City on the Edge of Forever"
Kirk and Spock follow Dr. McCoy into NewYork City of the 1930's, where the Captain falls in love with social worker Edith Keeler. He then learns he must prevent McCoy from saving her life to preserve history. Kirk, heartbroken, stands by helplessly as Edith is killed in an auto accident. And when returned to the present, he responds coldly to the Guardian's offer of other journies [sic] in time.
