The series focuses on the escapades of the eponymous "Gummi Bears," anthropomorphic bears who are the last remnants of a once-great civilization of Gummis that fled the land centuries ago when humans, jealous of the advancements and magical skills of the Gummi Bears, forced the species into exile. Now regarded by most of humankind as fairytales, the show's main cast of Gummi Bears (six in number at the outset of the series, increased to seven during the third season) live in the vast subterranean warren of Gummi Glen in the medieval kingdom of Dunwyn. The Gummis' modern adventures begin when they are discovered by a human boy named Cavin who happens to have a Gummi Medallion. After he accidentally enters the colony's underground home of Gummi Glen, they capture and interrogate the boy as to how he gained the medallion. During the questioning, Cavin escapes after Tummi inadvertently gives him Gummiberry Juice to drink, but refuses to cause any harm and attempts to befriend the reclusive bears. Impressed by this civilized behavior, they make him swear to keep their confidence and make him a privileged friend of the colony. Later, the medallion magically unlocks the colony's Great Book of Gummi, an essential reference guide to the forgotten knowledge of the Gummi Bears. Inspired by its writings, the colony resolves to rediscover their heritage and help Dunwyn defend against evil.