Spirou and Fantasio's friend, the Count of Champignac, asks them to join him in Australia, where he has heard that an ancient monolith is still standing. When they arrive, Champignac's colleague, Walker Donahue, informs them that Champignac has been abducted by a local gangster named Sam. The monolith they're after stands in the vicinity of an aboriginal mining village, prey to white prospectors trying to steal indigenous resources. Spirou and Fantasio must save Champignac from Sam's clutches while standing by the aboriginal people.