Every Mother's Day, Robots made in Mom's Friendly Robot Company factories around the world give sentimental gifts and cards to the owner of the corporation, Mom. However, this year, Mom, bitter about a romantic affair that had ended 70 years prior, orders the entire Robot population of Earth to rebel and overthrow humanity through a Universal Robot Controller that transmits to every robots' antennas. This doomed romance had been with a younger Professor Hubert J. Farnsworth, then an employee of the Friendly Robot Company. When Mom insisted that the Professor's latest design, a children's toy named Q.T. McWhiskers, be changed to an eight-foot-tall death machine to be sold on the intergalactic arms market, the Professor, enraged, stormed out of the room, and they hadn't seen each other again since.
Wishing to end the Robot rebellion and save humanity, Mom's three sons, Walt, Larry, and Igner, cooperate with the Planet Express crew to obtain the robot control Mom keeps in her bra. Their plan is to bring Mom to her rustic cabin in the Bronx, have the Professor seduce her, remove her bra, and use the control to end the rebellion. They give the crew a non-computer-drawn map. Deprived of technology, the crew must be guided by Fry's 20th Century low-tech knowledge. He builds a wagon, albeit with oval wheels, and brings the Professor to the Bronx.
When the Professor and Mom meet, their love is rekindled. Despite a reenactment of their parting argument, they erupt into a "whirlwind of hot, dry sex". Everyone else comes in because the Robots had made their way to the Bronx. They search everywhere for her thrown bra and find it on a fan, which evades their attempts to grab the bra. Mom stops the rebellion, but dumps the Professor after learning of their plot. Back at Planet Express, the Professor engineered albino-shouting gorillas to yell Mom's name from the rooftops.