Garfield and Odie experience a personality swap, caused by touching a statue, which leads to a couple of misunderstandings.
While walking down the street with Garfield and Odie, Jon mentions finding a place to eat. Garfield is fond of the idea, especially since he does not want to date Gwendolyn with an empty stomach.
Their search for a restaurant is interrupted by a woman named Madame LaFong, who invites them to her "Mystic Museum", to offer them A "solving mystery of the ages". Jon, willingly, agrees to learn the mysteries of the ages, paying the museum's owner for an entrance as Garfield reminds Odie not to touch the objects on display.
One of the presented artifacts is a "cursed mage orb", said to cause children who touches, grow into an encyclopedia sentient. Garfield considers such a curse is worth its name. Jon mistakes a wall-attached fire extinguisher, for a nineteenth century Mayan temple bell, most probably as a joke.
Meanwhile, Odie sniffs a statue, which causes the object to emit a yellowish energy around Odie. When Garfield tries to take Odie away from the radiant statue, he also gets struck by the same energy. It turns out, that the pets have found The Idol of Id - an artifact said to swap the minds of the two people touching it. At first Jon refuses to believe in such ability, and takes in question, paying for seeing two statutes and one fire extinguisher; Madame LaFong claims the idea of paying is supposed to be one of those mysteries.
Feeling cheated by the museum owner, Jon takes his pets back home, without noticing that Garfield is walking on four legs, and Odie is walking on two legs. It slowly turns out, that the Idol of Id did swap Garfield's and Odie's personalities. Back home, Jon serves his pets dinner and witnesses Odie devouring lasagna similar to Garfield usual behaviour. While Jon becomes amazed, Garfield, in Odie's body leaves home, searching a gift for Gwendolyn. Shortly after, Jon discovers Garfield barking and drooling the same way Odie normally behaves. Even the way Jon has shown gratitude for Odie's meal which does not match Garfield's, leading Jon to confusion.
The confusion is partially lightened up by the reminder of Madame LaFong's statement about the statue's abilities to swap minds. As a conclusion, Jon brings Odie (as Garfield)to find Garfield (as Odie).
In the downtown, Brick is attempting to convince Gwendolyn for a date with him and not with Garfield. The female firmly insists on going out with Garfield, despite her ex calling Garfield a "fat, lazy wimp" and accusing him of being weird. The appearance of Garfield in Odie's body causes the two cats to become amazed. Garfield does not understand, why he is being called "a dog" by Brick. The aggressive behavior of the latter causes the body-swapped Garfield to flee and leave the flowers he brought Gwendolyn as a gift. At the same time, Jon and Odie (still as Garfield) split up during the search for Garfield (still as Odie).
Odie in Garfield's body finds Gwendolyn and she believes that her date is behaving weirdly, both due to a lick in lieu of excuse for delay and a bone as a gift. While watching her date biting his back, she becomes irritable and admits that she always manages to meet weirdly behaving guys. At the same time Garfield in Odie's body realizes that his mind has been swapped with Odie. Brick's chase gets reversed, when Garfield barks at the chaser and admits, that chasing cats is fun. Gwendolyn finally gets upset with her date, when Odie in Garfield's body runs around her in circles.
Finally, the pets with swapped bodies find each other and Jon takes them back to Madam LaFong, hoping to reverse the swap. The owner of the Mystic Museum is shocked to discover that the statue actually worked. When Garfield and Odie jump on the Idol, the artifact breaks in pieces. Nevertheless, they manage to get their own bodies back. While gathering remnants of the statue with the museum's owner, Jon admits that this artifact is too dangerous for the world.
At the end of the episode, Garfield cracks a joke that if he ever needs new mind, he will want Odie's mind, since it was never used. It turns out, that the Idol of Id (even after being destroyed) swapped minds of Jon and Madame LaFong, since Jon (now in LaFong's body) leads the pets home while LaFong (in Jon's body) closes the museum's door.
- Gwendolyn initially calls Garfield a "gentle-cat", a variation of "gentleman".
- A similar plot would later used in the episode "Freaky Monday" from The Garfield Show.