Folleg disappears into thin air. But before that, he can still toss a suitcase to Spirou and Fantasio, which they are to take to Africa. There, in the Niokolo-Koba area, strange things are happening: elephants, hippos, buffaloes, and even warriors from the Bassari tribe are disappearing without a trace. Together with their new friend Prugal Knape, the friends investigate the matter.