In this exciting volume, Jommeke and his friends encounter an old acquaintance: disguised as an inconspicuous gardener, the crook Sam Peper is still searching for a treasure at Pimpeldon Castle. The children, of course, are quite inconvenient for him, and he tries to eliminate them. However, thanks to a fantastic invention by Filiberke, they manage to get the upper hand on him. Whether there is actually a treasure in the end and what role a distant relative of Sir Pimpeldon plays, you will find out in this standalone adventure.