The Mutants Are Revolting
The Planet Express crew is hired to make their 100th delivery, inspiring Bender to organize a gigantic party. The assignment is to deliver a soufflé to the wealthy and snooty Mrs. Astor. They cannot drop it, because it contains the nitroglycerine she needs for her heart, so Bender carries it: he's gyroscopically stable, and helps safely get the soufflé through asteroid fields and over a rickety rope-bridge. As the Farnsworth family has been in New New York for over 200 years, she invites them to come to the fancy Astor Endowment Fundraiser. At the gala, Mrs. Astor tells a tale: As a youth, she and Mr. Astor were traveling on the landliner Titanic, which struck a mailbox and sunk into a sinkhole. 2000 souls were lost, including Mr. Astor. In his honor she established the United Mutant Scholarship Fund, which funds the university at which the mutants who live underground learn to fix the sewers for the land dwellers. Leela is offended; Mrs. Astor really just wants to keep the mutants busy so they won't start jabbering about equal rights. Fry accidentally lets it slip that Leela's a mutant... so she is banished underground, where she returns to her family.
As Bender prepares for his party, a guilt-ridden Fry decides to help Leela. He goes to the Mayor to stand up for her, but when the Mayor finds out that the Planet Express knowingly harbored a mutant, the crew ⎯ minus Bender, who stayed home ⎯ is sentenced to two weeks underground. They meet up with Leela, who is angry at everyone on the surface for the deplorable conditions mutants must live in. Fry thinks that after two weeks underground, he'll truly understand the mutants' plight. Leela tells him that if he really wanted to understand, he'd dive into the toxic muck and get mutated himself. Fry declines, confirming to Leela that Fry is "all surface." The crew, looking for a place to spend the night, finds the wreck of the Titanic. In a safe they find a priceless, quantum-force, gemerald ring, which can fire a powerful laser beam. The ring's band has a romantic inscription on it from Mr. Astor to Mrs. Astor. Meanwhile, Bender's party is in full swing, but when Bender sees a photo of the missing crew, he just can't enjoy himself anymore. He throws all the revelers out of the building, and sits down to mope. Back underground Fry, feeling guilty for ruining Leela's life, strips down to jump into the toxic ooze so that he can truly find out what it means to be a mutant. Leela tries to stop him, but she's too late. Fry emerges as the most hideous mutant of them all: three-eyed, horned, be-tentacled, and with tons of melting flesh. Even Leela can barely stand to touch him.
They hold a rally for mutant rights, at which Devo plays a set. The mutants begin a revolution, sending toxic ooze to the surface and waving protest signs through open manholes. The next step: bend the Westside pipe-way to return all sewage to the surface. Bender is happy to be recruited for the job. Soon the streets of New New York are flooded in toxic sewage, and Leela rallies the mutants for the Million Mutant March to the surface. The city solves the sewage problem by pumping all the sewage into Madison Kew Garden, but the protesting mutants arrive, chanting "Two, four, six eyes! Mutant people will arise!" Leela demands equal rights, and access to the surface. The sewage from Madison Kew Garden is released in a tidal wave to try to wash the mutants back underground. Fry uses the gemerald to part the wave of sewage like a mutant Moses. Although Mrs. Astor is unmoved by the return of the gemerald, Fry has more to tell her. It turns out there were mutants working below-decks on the Titanic, in the sewage galley. An elderly mutant comes forward. As a young girl, she worked on the ship. When the ship began to sink, her mother tried to get her onto the nearest life-car. All the cars were taken... but Mr. Astor was overcome with compassion, and gave up his seat to the mother and child. The woman turns out to be Leela's grandmother. Fry tells Mrs. Astor that if she truly wants to honor her husband's memory, she should treat the mutants with dignity, as Mr. Astor did. Finally touched, she has the Mayor grant the mutants their freedom. Leela leans in to kiss Fry... whose mutant form suddenly slides off of him. It transpires that Fry wasn't mutated at all. He was fortunate enough to step directly into the mouth of... Mr. Astor, who was mutated himself after the wreck of the Titanic, and had been living in solitude ever since. Mrs. Astor tearfully hugs her slimy, long-lost husband. "Hooray!" shouts Zoidberg: "A happy ending for the rich people!"
Leela takes her now-liberated parents and grandmother to Planet Express to show them where she works. "Ohhhh," says her mother: "Was there a fire?" Bender says the party was the greatest party ever, and he never needs to have another one... but throws one for his friends anyway. All dance together happily.