A mishap involving a microwave oven and a supernova throws the Planet Express staff back in time to 1947 where Fry has a fateful encounter with his grandparents, Dr. Zoidberg meets Pres. Truman and Leela & Prof. Farnsworth wreck an Air Force base.
Bender sets up a successful waste disposal business. But because he dumps everything in the sewers, the Sewer Mutants revolt and sentence Bender, Leela and Fry to be dumped in the Mutagenic Sewage lake. Somehow two robed mutants with an interest in Leela manage to persuade the Supreme Mutant to let them go.
Fry, Leela and Bender are enslaved on the planet of the original Egyptians to build a monument to the Pharaoh. When the Pharaoh dies, Bender rewrites prophecy to take his place, but keeps Fry and Leela as slaves to build an even bigger monument.
Fry learns that Star Trek had been banned on Earth centuries earlier and goes on a quest with Leonard Nimoy's Head to find the last remaining episodes. He encounters the re-embodied cast of the original TV show who are prisoners on the planet of a very devoted fan.