After playing a mean trick on Nermal, Garfield loses his memory. Nermal tricks Garfield into thinking he's an alley cat named Ichabod.
Nermal is visiting the Arbuckle house, doing various cute things. Jon enjoys Nermal's antics, while Garfield hides his disgust with a mask of his face grinning. Garfield pretends to be able to tolerate Nermal while Jon is around, but otherwise makes no secret of how he feels.
Garfield sets up a complex trap for Nermal, which launches Nermal out of the house and into a trash can. While laughing, Garfield gets hit on the head with a bowling ball. When Nermal re-enters the house to confront Garfield, he finds that Garfield has lost his memory. Taking advantage of the situation, Nermal tells Garfield that he's an alley cat named Ichobod who only eats out of trash cans. Convinced, Garfield looks around the city for trash cans. Meanwhile, Nermal takes over the house, putting up pictures of himself around the living room, as well as a statue of himself.
At one point, Garfield encounters cat brothers Teno and Geno in an alley. Garfield introduces himself as Ichobod and joins them. They later arrive at Vito's, where Teno and Geno frequently eat out of the garbage. However, they are interrupted by a bulldog named Crusher, who often creates disturbances in the alley (which Vito believes to be due to Teno and Geno). Garfield and Crusher go on the chase, which eventually leads them back to the alley by Vito's. Garfield gets Vito's attention by banging a trash lid, which results in Vito calling animal control. Crusher is then captured and hauled away; the alley becomes safe for the cats. Garfield, upon tasting lasagna, gets his memory back.
Returning home, Garfield meets Odie, who is happy to see Garfield with his memory regained. Garfield then inadvertantly finds out about Nermal's trick. He then arranges another, less complex trap. Pretending to have still lost his memory, Garfield offers to be Nermal's slave. Nermal happily accepts. Garfield "starts" by adjusting the living room chair Nermal is sitting on, which launches Nermal into a box on top of the trash can from earlier. Garfield, still acting amnesiac, wraps him up, then launches him in front of a mail truck, which picks up the package.
Later that night, Jon wonders where Nermal has gone. Garfield then brings Jon's dinner to Teno and Geno, who are in the tool shed in the backyard.
- Parts of the plot were loosely based off of "Forget Me Not".