The show took place inside a red, yellow and blue box, with the main characters, Cat and Dog, being controlled by puppeteers from inside the box. The puppets would draw pictures, tell stories, sing songs, and play jokes on one another (mainly typical slapstick). The puppets were voiced by Pat Coombs and Keith Chegwin.
It was created by Leslie Pitts, and Anne Wood (who had only recently founded the now famous Ragdoll Productions).