The Planet Express crew makes its one hundredth delivery: a souffle to a rich, old widow, Mrs. Astor. After making the delivery, she invites them to a fun raiser for mutant scholarships to Brown University. Fry accidentally reveals that Leela is a mutant, banishing her back underground.
Bender, meanwhile, throws a 100th delivery party while the rest of the gang fights for Leela's rights and ends up getting sent down to the sewer for harboring a mutant. Fry turns himself into a mutant and leads the mutants to march above ground for equal rights. Bender, missing the gang, comes underground and reverses the sewers to create backflow up above.
Oh and there was a Land Titantic. Yeah, a second Futurama Titanic joke. One of the passengers? Mr. Astor. While underground, the crew discovers a list revealing there were mutants aboard and that Mr. Astor gave up his seat in the life car to a mutant... Leela's grandmother to be exact.
Mrs. Astor is so moved, she gets the mayor to allow mutants to stay above ground. Oh and it turns out Fry is no longer a mutant, he pops out of Mr. Astor's body and every parties.