In the watery depths of cybersite Aquari-yum, the kids and Hacker go in search of a giant cyber-slug, who feeds on pure energy. The kids and Digit travel underwater in two separate vessels, but Hacker has a listening device that taps into their communications system, allowing him to overhear their plans and track every move they make. The kids outsmart Hacker by devising a series of codes so they can send messages back and forth in secret — even though Hacker can hear what they’re saying. Topic: codes with rules.

Originally released by PBS, 2002. Streaming video file encoded with permission for digital streaming by Infobase on January 26, 2022.