The combined explosions of a supernova and Fry putting metal in the microwave hurtle the Planet Express crew back in time to 1947. They land at Roswell, New Mexico, where a shattered Bender is mistaken for UFO debris, Zoidberg is taken in for an alien autopsy, and Fry accidentally kills his grandfather, Enis, in a nuclear explosion.
A Planet Express mission to Robot Santa's colony on Neptune leaves the murderous robot trapped in the frozen sea, and Bender takes over as Santa, vowing to bring peace and goodwill to Xmas again. But when Bender is mistaken for the real Robot Santa, he is arrested and sentenced to death.
When the Professor fine tunes his "What-If" machine, Bender discovers what it would be like if he were human, Fry discovers what it would be like if life were more like a video game, and Leela discovers what it would be like if she found her true home.
Bender falls deeply in love with the Planet Express ship autopilot's female voice setting. Meanwhile, Fry searches for the perfect candy heart to properly convey his feelings for Leela.
When Bender disposes nuclear waste in the sewers, the angry mutants drag him, Fry, and Leela down to the depths to be mutated. As they attempt to escape, Leela makes an incredible discovery about her true heritage, finally meeting her parents for the first time.
When Amy's parents' ranch is hit by a dust storm that blows away their herd of buggalo, Kif sets out to prove his masculinity by rounding up the herd, only to become entangled with the native Martians.
Bender fears that nobody will remember him after he dies, and sees his chance for immortality when the crew is enslaved on the planet Osiris 4. Posing as the planet's new pharaoh, Bender orders a humongous statue built in his honor, and quickly goes mad with power.
Bender is accidentally shot out of the ship's torpedo tube and becomes lost in space. Floating through the ethereal darkness, Bender becomes inhabited with tiny alien life forms, but has trouble playing God to their unyielding prayers.
With Planet Express in financial trouble, Fry nominates a flashy businessman from the 1980s to replace Professor Farnsworth as CEO of the company. That Guy goes on to sell Planet Express to Mom's Friendly Robot Corporation, putting everyone out of a job.
Leela endeavors to become the first female blernsball player, but her lack of depth perception hinders her skills. Nevertheless, she becomes the pitcher for the New New York Mets, purely for her novelty value.
Bender receives culinary lessons from the great chef Helmut Spargle, and puts his skills to the test on national television when he competes against Elzar on "Iron Cook". Meanwhile, Dr. Zoidberg accidentally destroys Professor Farnsworth's ship-in-a-bottle and pins the deed on Fry, only to be struck with remorse afterwards.
Fry leads the crew on a quest across the galaxy to regain the forbidden 79 episodes of "Star Trek: The Original Series", where they encounter the original cast of the show - as well as their captor, an obsessive energy being named Melllvar.