Fry puts a metal popcorn pan in the microwave while a supernova occurs nearby, causing the radiation of both to rip open a time portal that sends the Planet Express crew back in time to Roswell, New Mexico in the year 1947. Bender's body is broken to pieces during the crash and Zoidberg is found by the U.S. military among the debris, and both are taken to Area 51 for experimentation. The crew requires another microwave to return to the 31st century, so they try to retrieve one without altering history. Meanwhile, Fry meets his grandfather Enos and begins fearing that he will cease to exist if his grandfather is killed. While trying to save him, however, Fry accidentally brings about Enos' death when he takes him to a house which turns out to be in the middle of a nuclear testing range. However, Fry continues to exist due to either Enos getting Fry's grandmother pregnant before dying, or was an unrelated man whose surname happened to be "Fry". He ends up having sex with his grandmother. Since Fry has already changed history, the rest of the crew decides to launch an attack on Area 51, retrieving Bender, Zoidberg, and a microwave by force and allowing them to return through the closing time portal back to the 31st century.