Emmett Brown is in an undisclosed location outside Hill Valley, California. He sets a video camera to track his body in order to videotape a message for Marty McFly. He explains that it is October 21, 2015, one hour before Marty, Doc, and Jennifer Parker arrive from 1985. He explains that when he traveled to the future, he discovered that there was a nuclear holocaust that occurred on October 21, 2045. He tracked it down to four inventions: the food hydrator, self-lacing shoes, the hoverboard, and the Mr. Fusion home energy reactor.