One day three children from Earth named Matt, Jackie, and Inez are called to the land of Cyberspace by Motherboard, its guardian to defend her from a virus as unleashed by a villain named Hacker. Motherboard is the guardian of Cyberspace, a dimension where computer networks exist as physical locations known as cybersites. In each episode the kids must work to defend the site they are visiting from the work of the nefarious villain Hacker, or The Hacker as he puts it, and stop him from accomplishing his goal of taking over Cyberspace. The kids are teamed up with Digit, a former henchman of Hacker who betrayed him after he betrayed Motherboard. In each episode the children must make use of a different mathematical concept to help them out. In the United States on PBS the show was followed by a segment called "Cyberchase For Real" where the day's topic was placed into a real-life situation.