The series features three magical hippo-like creatures called the "Fimbles", who are portrayed by "skin" actors in complex, fluffy animatronic suits and all look quite similar apart from their colour and size. The characters explore Fimble Valley and can find things through a special "sixth sense". When the Tinkling Tree tinkles its bell-like blossoms, it makes the nose, fingers and topknot of one or more Fimbles twitch as they get the "Fimbling Feeling". This tells the character(s) that they are going to find something. It may be a natural phenomenon - a patch of sunlight for example, an everyday object, e.g. a tambourine, or something which would be totally inexplicable in the real world, such as a puddle of blue "galoo". Whatever is found becomes the catalyst for the episode's adventures and the trigger for the Fimbles' creative play. The other characters featured are large scale puppets who normally help out the Fimbles with something. The snouted and concentrically-ringed appearance of the Fimbles was based on the eponymous villains of Lucy Anna and the Finders, written and illustrated by Sarah Hayes. Although Hayes is cited in the credits of Fimbles, and she was involved in adapting the characters for the television series, the implacably omnivorous Finders (who, throughout the book, threaten to eat Lucy Anna) have nothing else in common with the Fimbles.