Zagor and Chico attempt to rebuild their hut, destroyed in the preceding adventure, but the incredible Going-Going has eaten up all of their tools. Then, in Maysville, they meet two old acquaintances, the German scholars Kruger & Meyer, who, together with their colleague Weiser, are headed for Missouri to study some unexplainable mutations. When the two have left, Zagor and Chico discover that their guides are in fact, criminals!
