A bird has discovered a strange blue ball in her nest. After deciding she doesn't need it, she discards it into the river running below her tree. It turns out it's #520's pod, and it activates. Now the experiment is wreaking havoc over the island with it's huge behind by bouncing and shaking the ground. So, Lilo and Stitch must capture it, but Gantu is on it's trail too.

Mertle has got a new dog; Gigi. Little does she know, it's really Experiment #007, a dog that can keep everyone in the neighbourhood awake with it's loud yapping. So, Lilo and Stitch must protect it from Gantu, but have to go to a dog show to do it.

Mrs. Hasagawa is watering her vegetables innocently one morning. However, she activates Experiment #613, Yaarp, which is designed to destroy buildings with it's sonic blasts. Lilo and Stitch are hot on it's trail, when it yarps, and because of Stitch's super hearing, Stitch is temporarily deaf. So, when Jumba says only someone with no ears could be safe from Yaarp, Pleakley is on the stage as an Experiment Hunter. Pleakley catches Yaarp, but Stitch's plan to deter Gantu away from the hunt goes wrong, and he captures Stitch. And now he is offering Lilo a trade: Stitch for Yaarp.

Lilo & Stitch learn that Mrs. Hasagawa has adopted a lot of cats that are not cats at all but experiments.