A flying saucer lands in Washington D.C. The extraterrestrial traveler, Klaatu, wants to arrange a meeting to promote world peace, in the hope that humans will evolve beyond their violent tendencies. When Klaatu exits his spaceship, a nervous soldier shoots him. In order to better understand Earthlings, Klaatu leaves his 8-foot robot Gort in charge of their saucer and poses as a human. Known only as "Carpenter," Klaatu rents a room in a boarding house and befriends a compassionate woman and her teenage son, and also meets a scientist named Barnhardt. As government agents try to locate Klaatu, he waits for a crucial moment when the Earth will come to a standstill, and all electrical energy will be frozen for 30 minutes, as per the instructions of the higher powers that sent him.