A mouse tricks a fox, owl, and snake into believing it is going to have lunch/tea/a feast with a gruffalo, a made-up creature. When each animal asks what a gruffalo is, the mouse describes its scary features. When they see the gruffalo with the mouse, each animal gets scared and runs away. In the end, the mouse convinces the gruffalo that it is feared by all, but then says its favorite food is gruffalo crumble, scaring off the gruffalo. The mouse is left alone to enjoy a nut in the woods.