Asdrúbal becomes a rare piece on display at the Dum-Dum Museum and becomes frustrated by the obligation to entertain visitors. One day, he sees something unexpected in the sky: a blue butterfly. He ends up making friends with Raimundinho, a boy always ready to plot something and, as usual, things don’t go exactly as planned. In this adventure, the yellow monster experiences an unusual situation, making the reader question what place monsters should occupy in the world.