It's Lilo's birthday, but no one has remembered. So, she decides to give herself her own party. However, during the day, Experiment #303 is activated and wipes Lilo's, Stitch's and Gantu's memory. Lilo and Gantu, who think they are Martha and Lenny go after Stitch, who has returned to his natural destructive programming, and so they think is a criminal.

Experiment 020: SLICK

Chaos ensues as Slick, a fast-talking experiment who can sell anything to anyone, teams up with Lilo and Stitch to sell candy bars for the Hale Kaiulu's annual fundraiser. Lilo soon learns the hard way that Slick is not designed to stop, and she and Stitch must reclaim their household items before it gets too late.

Experiment 029: CHECKERS

Lilo is angry and under appreciated about her float not getting chosen for the parade, and being grounded (along with Stitch) by Nani and Pleakley.

Experiment 267: WISHY-WASHY

Lilo learns a valuable lesson in being careful what you wish for when Experiment 267 is activated.

Experiment 540: PHOON

Lilo quits experiment hunting go to Hula Hip Hop Fusion school. Meanwhile, Experiment 540 is unleashed, causing Gantu to take a bad blow to the head. Jumba new device causes Phoon to mutate into a giant monster. And Gantu thinks thing like 625 and Hamsterveil are just figments of his imagination.