Professor Barbenfouillis and five of his colleagues from the Academy of Astronomy travel to the Moon aboard a rocket propelled by a giant cannon. Once on the lunar surface, the bold explorers face the many perils hidden in the caves of the mysterious planet.

《五个孩子和一个怪物》故事是从一个搬家的日子开始楔入的新居临海，四个孩子把在婴儿车里酣睡的小弟弟抛在一边，在一望无垠的沙滩上挖开了。突然，从沙子底下钻出来一个怪物，一双蜗牛般凸起的眼睛，身上乱蓬蓬的毛像猴子一样。它自称“沙仙”。