Through a hole in the baseboard of a workshop, owned by an inventor named Doc and his dog Sprocket, is the world of the underground caverns, grottos, lakes and streams, and flora and fauna that is Fraggle Rock, home to the Fraggles. Fraggles are furry creatures that are 18 inches high and come in all kinds of colors and personalities. They universally adore music and they love to play. In fact, all Fraggles have a 20-minute workweek. The rest of the time, they party!

The five main Fraggle characters who live in the Rock are Gobo, Red, Mokey, Wembley and Boober. Travelling Matt Fraggle, Gobo's uncle, is the one adventurous soul who has ever ventured out in the world of the humans, making observations about these "silly creatures" and sending postcards back to Gobo.

In addition to the hole in the baseboard, another entrance to Fraggle Rock leads to the community of the Gorgs, giant (15-foot) creatures who are the Fraggles' nemeses. The Gorgs consist of Pa, Ma and Junior.

The third race of beings that inhabit the world of Fraggle Rock are the tiny green Doozers, who stand knee-high to a Fraggle. An industrious group, Doozers live to work, and think that the Fraggles are totally frivolous.

The antagonism that exists between these three groups of characters is belied by the fact the unbeknownst to them, the Fraggles, Gorgs and Doozers share a complicated ecosystem and are actually dependent upon each other for their survival. For instance, the Fraggles have a ritual whereby they bang on pipes in Fraggle Rock which are actually the water pipes in Doc's workshop - leading Doc to fiddle with the pipes, which then sends water into Fraggle Pond, the spillage from which powers the Doozer stick factory and is also the source of the Gorg's well water, which waters their garden from with the Fraggles get their main food (radishes) and the Doozers get their main building component (also radishes).