Experiment 234 was the 234th genetic experiment created by Jumba with Hämsterviel's funding. She was designed to eavesdrop on private enemy conversations. 234 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai.
234's pod was found by Gantu in a playground, where Lilo and Stitch were present. Gantu then attempted to escape with the pod, but Lilo and Stitch were able to get the experiment pod back from Gantu after a brief struggle. Unfortunately, a pair of kids then soaked Lilo and 234's pod with their super-soakers, activating the experiment.
When Lilo brought Shush home, the latter eavesdropped on Nani talking to David on the phone, to which Lilo mistook as her older sister trying to insult David. After Nani cleared everything up with Lilo, she reprimanded her younger sister for eavesdropping on other people's private conversations.
However, Lilo later used Shush to eavesdrop on Mertle dismissing her dolls, despite Stitch telling Lilo otherwise. She mistook Mertle's statement as a dismissal of the hula girls. They believed Lilo at first when she notified them and shunned Mertle before taking sides, but were more strict about always being told what to do.
Shortly after, an escaped Hämsterviel on a PC screen talked Mertle into catching the remaining experiments in place of Gantu (who had been fired for his incompetence earlier), to which she accepted his offer. He then put a special mind-control headband device on Mertle's head, which hypnotized her into an android.
After hanging out with the hula girls for a while, Lilo decided to go check on Mertle and took Stitch and Shush with her. They soon ran into Mrs. Edmonds, who was carrying several boxes of Mertle's old dolls that she was giving away, thus revealing what Mertle was really talking about earlier. Lilo suddenly felt guilty about eavesdropping.
Lilo, Stitch and Shush eventually went to Mertle's house to apologize. However, Mertle ambushed them and then immobilized Shush. Gantu soon intervened and attempted to recapture Shush so as to redeem himself. After a long battle, Lilo and Stitch were able to defeat Hämsterviel and rescue Shush.
Later, Jumba removed the mind-control headband from Mertle's head, which reverted her back to her normal self, and Shush was shortly after found a one true place with Cobra Bubbles as a CIA operative.
The first 624 experiments, including Shush, were rounded up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.
It is unknown whether or not Shush participated in the following battle between the experiments and the Leroy clones.
The Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song "Aloha ʻOe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
- Shush's pod color is green.
- Lilo and Pleakley erroneously refer to her as male in her debut episode.
- Shush is described by the experiment computer screen as, "Experiment 234. Primary function: Eavesdropper."
- Shush is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.