After making their 100th delivery, for which Bender organizes a huge party, the Planet Express crew is invited to a fund raiser for giving sewer mutants the needed donations to keep them away from the surface. Seeing how upset Leela is by this, Fry publicly lets slip that she is a mutant living illegally on the surface, causing her to be banished to the sewers for life. Feeling guilty for ruining Leela's life, Fry and the Planet Express crew appeal to the mayor to let her live on the surface again, but they are instead banished to the sewers for two weeks for knowingly harboring a mutant on the surface, minus Bender, who is enjoying the party. To appease Leela's anger and understand the life of a mutant, Fry jumps into a pool of toxic waste and emerges as a hideous blob. Leela is moved by Fry's sacrifice and decides to lead a mutant rebellion against the surface people by getting Bender, who ends up stopping the party after realizing it is no fun without the rest of the crew, to bend the giant sewer pipes together, thus backing up all the pipes around the city and flooding the surface with sewage. The mayor complies to the mutants' demands for equal rights, allowing them to finally live on the surface. Furthermore, it is revealed that Fry had not mutated, but was merely stuck in the body of another mutant. Afterwards, the Planet Express crew has a second "100th Delivery" party since they missed out on the first.