Professor Farnsworth announces to the crew that the university is bringing him up on disciplinary charges. The crew accompanies him to Mars to hear the charges against him, but instead in turns out to be a surprise 150th birthday party. A short film is shown to celebrate Farnsworth's life, but it leaves him feeling unhappy and depressed. He also feels he has so much left to achieve with so little time left. Fry attempts to encourage Farnsworth by telling him that he could live for another 100 years, to which Leela replies that he couldn't because the Sunset Squad robots come and take you away when you reach 160.
Farnsworth realizes that there is nobody to carry on his work once he has gone and decides that it is time to name a successor. The crew argues amongst themselves as to who they believe that Farnsworth will pick and after several days they are all called into his lab for the announcement. Cubert, a clone of the Professor, is named as the successor. It quickly becomes evident to everybody that Cubert has no intention of following in Farnsworth's footsteps, preferring to be something useful, like a teacher's aide, a prison guard or a science fiction cartoon writer, believing all Farnsworth's inventions are useless. This breaks Farnsworth's heart, realizing that there will be no one to carry on his work and his wondrous inventions will go unfinished.
Farnsworth records a message for the crew, telling them that when they watch it he will be gone. He continues to explain that he has been lying about his age and he is really 160, and has notified the Sunset Squad robots to take him away.
The next morning when the crew discovers Professor Farnsworth's fate, they decide to go and rescue him. They use the Smelloscope to locate the Professor flying to the Sunset Squad fortress. To gain entry Fry impersonates Farnsworth using Cubert as his hump, while Leela and Bender are the guards that escort him. Cubert has the same DNA as the Professor so when the robots sample it, they believe that he is the Professor and allow them in. The crew locates Farnsworth who is connected to a machine over several points on his body, as the crew start to carefully disconnect them they are discovered and are forced to flee quickly, ripping Farnsworth away and racing back to the ship. They are chased, weaving in and out of the tall buildings by several of the Sunset Squad robots. Cubert is knocked unconscious by a closing door as the crew make it safely back to the ship. As they begin to take off, several of their pursuers fire shots at their engines causing them to disengage. Fry begs Leela to fix it so that they can escape, but Leela explains that only Farnsworth knows how the dark matter engines work. They try to revive him but are unable to wake him from the catatonic state. At this point Cubert regains consciousness and reveals that he now understands how the engines work and is able to repair them allowing them to escape.
Later when Farnsworth has recovered, Cubert tells him that he wants to be just like his father.