Plot: Despite Francine's early hints, Stan completely forgets their anniversary, only remembering that it's time for the CIA's annual fishing trip. He leaves in a hurry--dropping food on the bed and soiling the stairway since he didn't have the time to go to the bathroom--all left for Francine to clean.
During the day, Francine still has hopes that Stan will remember and do something romantic for her, something that Klaus and Roger highly doubt as they watch a taped episode of COPS from the previous year when police had to be called as Francine was beating Stan to a pulp for having forgotten their anniversary. Francine remains confident since she figures Stan has until midnight to come up with something. Meanwhile, Hayley gets invited by her boyfriend to go to Burning Man, something that she is less than enthusiastic about doing.
While midnight fishing with his co-workers, Stan eventually mentions that he's glad not to be at home on that day since it is the anniversary of a "huge fight" he and Francine had the previous year. When his friends ask the reason, he says it was because he forgot their anniversary but he never makes the connection. His friends wait for a while until Stan realizes in horror that he has again forgotten the anniversary. He shows up home looking to make amends, with an excuse that he did not forget and had just been trying to throw Francine off, and brings with him singer Whitney Houston for a private performance in exchange for a fix of cocaine. Francine is not impressed and vows that she will never forget what Stan did. He then hands her a card that is supposed to make everything better. When Francine opens it, gas comes out and knocks her unconscious. Stan then takes her to the CIA secret lab to have the last 20 hours of her life erased from her memory but the scientist performing the procedure gets the dials for years and hours confused and ends up erasing the last 20 years of Francine's life as she now believes that it is 1985. He also finds out that the procedure is irreversible. He tells Stan that he will have to make do and just hope that Francine eventually recovers her memory.
After bringing an unconscious Francine back home, Stan remains confident that she will remember their love as soon as she wakes up but, when she does, she doesn't recognize anyone. Francine freaks out about Roger the alien and Klaus the talking fish so Stan is forced to gas her again. Then a video presentation by "forgettable actor" Bill Pullman convinces Stan that the best way to handle the situation is to have Francine believe that she is indeed still 18 years old. But if she is told what has happened to her, her brain will implode He has her moved back to her old apartment and Hayley is to be her roommate. After getting rid of the old lady that was living in Francine's old place, Stan and Hayley fix up the place so that it looks like it's still 1985. While Francine wakes up to her fake youth, Stan, back home, reminisces with Roger the day when he met Francine and they fell in love: he gave her a ride. Then they ran over a raccoon who was then dying in agony. Stan shot it in the eye and Francine thought that it was a high act of compassion. Roger then suggests that Stan reenact this to try and bring back Francine's memory. He then has Hayley abandon Francine by the road, picks her up and tries to run over the raccoon that Steve sets free by the road. This time, however, he misses the target. The raccoon is unharmed and Francine won't let Stan execute it. He then drags Francine along as he tries to shoot the animal dead. It is all to no avail as the raccoon escapes and Francine now views Stan as a psychopath.
Back to the apartment, Francine throws a party. Jeff, Hayley's boyfriend, tries to drag her to the Burning Man event again but she is unwilling. Back home, Stan comes up with another plan to get Francine to remember their life together. He finds a dried flower that he gave her on the day of their wedding and goes to the apartment to show it to Francine. When he gets there, he and Hayley discover that Francine and Jeff ran off together to the Burning Man event. They follow them there and are joined on the trip by Klaus who was hiding in Stan's thermos and peed in his coffee, causing Stan to spit. But when they arrive, they are unable to find Francine, forcing them to rest for the night. But before they do, Stan shows Hayley the flower but warns her if she tells anyone about his soft side, he'll rip out her heart and eat it. The next morning, Stan finds Jeff, who admits that Francine left him as soon as they arrived and that he only took her to get Hayley's attention. Hayley, climbing out of a mountain of tired bystanders, admits that it worked and kisses him. Stan eventually finds Francine as she prepares to go on tour with a band. He shows her the flower but she confuses it with some sort of drug and eats it. When Stan is about to give up, after hearing from Francine that she would never "hook up with a stiff like him", the Burning Man gets accidentally ignited by a smoking paraglider and Stan saves Francine from a fiery death. He brings her to a recovering tent and pledges his love to her as she vomits repeatedly on his shoes. All this brings Francine's memory back.
On another front, Steve asks out a girl from school, Lindsay Coolidge, and is surprised when she accepts on the condition that he can get a date for her friend, Jewel. The girl, however, is as ugly as can be and no human being will date her. So Steve gets Roger to take on the job. Disguised as a Jamaican, Roger, who had been bitter about never being able to leave the house, joins Steve and the girls at a dinner for a double date. All goes well, as Steve is successful in getting Lindsay to go back to his house, but all the while Jewel is getting quite hands on with Roger. While trying to escape Jewel's advances, Roger's costume comes off and she sees him as the alien he is. When Jewel runs to tell her friend the truth, Roger is forced to clobber her in the head with a frying pan. Lindsay sees what happens and sees Roger. She tries to run but Roger hits her on the head by throwing the pan at her too. As Roger and Steve stand over the two unconscious girls, Roger suggests that they should pin the assault on "black guys".
Stan and Francine come home only to find Roger and Steve with two girls tied up and gagged. The solution is obvious: take them to the CIA secret lab and have the last 24 hours erased from their memories. While this is done, Stan is relieved to find out that Steve was hanging out with the cute girl.