Hunting birds is something Garfield gave up long ago. It's like eating mice : he just can't do it ! But when he finds a nest full of what look like abandoned eggs, Garfield puts his feline pride to one side and decides to hatch them. Harry, the stray, doesn't agree with this plan; he would love to put the newborn birds right on his dinner menu.

It's Halloween and Garfield has dressed up as Catzilla, a fierce wild cat, to go out trick or treating. He has painted stripes on his fur and added false teeth to complete his disguise. But what he doesn't know is that the real Catzilla has escaped from the zoo, and the neighbors are terrified of running into him. Garfield is busy trick or treating, going from door to door to collect candy.

Odie's nocturnal energy leads to a garden encounter with a Martian; a body-switching thank-you gift leaves Garfield as a dog and Odie as a pampered cat; Garfield despises dog life, prompting their desperate efforts to revert the switch.

Another day has begun, and Jon is doing the housework. He realizes Garfield and Odie are really dirty and disorderly. But Jon has a stroke of luck: a salesman knocks at the door and quickly talks Jon into buying a very efficient cleaning robot. They shake on the deal and Jon puts the robot to the test.

Garfield and Odie watch the news about a villain named Silent Jack, who robs houses while the owners are away.

Nermal meets a cat called Agent X who claims to be a Secret Agent, but he is really a runaway cat trying to impress the crowd.