Beth Sanchez Smith(Cronenberg World)

Morty is very interested in Jessica, but lacks the opportunity to ever talk to her. With the annual Flu Season Dance coming up, Morty turns to Rick for a potion that can make Jessica like him. After a brief argument, Rick gives Morty a serum that has the genetic makeup of voles, a rodent that pair bonds with its mate for life. Morty asks if there's anything that can go wrong with the serum and Rick answers no. Morty leaves the garage lab. Then Rick quickly adds, "unless she has the flu."

At the dance, Morty uses the serum on Jessica, and it seems to be a success. Things are going well until Jessica begins to sneeze. The serum, which has piggy-backed onto the flu virus and has caused the virus to replicate in seconds, is seen to go airborne, entering the fruit punch and air vents. Soon everyone at the dance is affected by the serum (and flu). The students and faculty swarm around Morty, with each of them violently competing to have Morty for themselves, before Rick saves him. Rick later tells Morty that the serum doesn't affect anyone related to Morty by blood. Rick then quickly works to create an antidote. He decides to use praying mantis DNA.

Rick releases his antidote along with a second airborne virus. It appears to have been successful until the town starts growing mantis-like appendages. Now not only do they still wish to copulate with Morty but also have the urge to behead him afterward. This Mantis-love virus soon infects the entire population, all of which wants to mate with Morty.

Meanwhile, Jerry struggles with feelings of jealousy when Beth is called in to work late. DespiteSummer's warnings, Jerry decides to stop by St. Equis Hospital where Beth works. After a successful surgery, Beth's coworker Davin makes a move before being infected by the Mantis-love virus. Jerry busts in with a crowbar and beats him to death. Meanwhile, Rick and Morty travel to a secluded area and Rick begins to concoct a third virus to try and undo all of his previous work. Taking the DNA from several sources, including cactus, golden retriever, shark, and dinosaur, he creates a third airborne virus that results in turning the entire population into disfigured, humanoid blobs that Rick dubs "Cronenbergs." The world is soon overrun with these disfigured monsters, and Jerry and Beth fight their way through them to survive, eventually reuniting with Summer.

On a rooftop overlooking the chaos around them, Rick and Morty call each other out for their part in the end of the world; Rick blaming Morty for asking for the serum to begin with, and Morty blaming Rick for mixing random genes together and hoping for the best. Rick then ultimately decides that the situation is hopeless to repair, and uses his portal gun. The scene is now Rick and Morty's garage, with Morty congratulating Rick on saving the world from the love potion. Rick asks Morty for his screwdriver, and gladly begins to finish his invention from earlier. Just as Rick twists the screw the third time, the device violently explodes, instantly (and messily) killing Rick and Morty. The Rick and Morty from the previous scene then step out from the portal, and Morty panicks at the incredibly bloody garage with the corpses of him and his grandfather lying limp and burnt on ground; until Rick calms him down by telling Morty that he had to find an Earth in which it's Rick and Morty died so that they could come in and take their place. The episode ends with Rick and Morty, burying their dead bodies in the backyard. Morty, with a thousand-yard stare, returns into the house in a daze before sitting on the couch.

After the credits roll, Summer creates her own TV shows standing in a cardboard box while Beth and Jerry (now content) admit they don't miss Rick and Morty at all. Meanwhile, Cronenberg Rick and Cronenberg Mortytransport from a reality they call Cronenberg World in which Cronenberg Rick accidentally turned everyone into normal human beings.