Experiment 529 was the 529th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to dig underground tunnels and drill holes through planets and other surfaces. 529 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, with 529's pod landing atop a little boy's sand castle on a beach.
Later, a tidal wave washed over the shore, activating the experiment, which proceeded to escape underground.
In "The Asteroid", Digger was one of the six experiments that Stitch convinced to come with him and Lilo to save Earth from an approaching asteroid. Along the journey, Digger was shown digging restlessly into his seat. He later drilled a hole through the asteroid's core for which to insert the ship's hyperdrive engine into.
The first 624 experiments, including Digger, 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.
Digger participated in the following battle between the experiments and the Leroy clones by sending attacking Leroys into his underground tunnels.
However, 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.
- Digger's design was first revealed in a bonus feature trivia game on the original Lilo & Stitch DVD, before he officially debuted in Stitch! The Movie.
- Digger's pod color is normally purple. In one scene his pod was red, and in another it was purple.
- Digger is described by the experiment computer screen as, "Experiment 529. Primary function: Digger."
- Digger is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.