Searching for a flower that transforms whoever smells it into a mad murderer, a scientific expedition has penetrated the unexplored area beyond the Watanka River. Zagor and Chico, upon invitation by the commander of Fort Pioneer, follow the tracks of the expedition and discover the mysterious tribe of the Tiwa-Tiwas and their mysterious, monstrous rites...
Trampy has established a travel agency, Ulysses’ Travel Agency, which offers Boat City tourists the thrills of Frontier life, organizing mock Indian attacks, mock holdups, mock encounters with gunslingers. But in the final act, we go from make-believe to reality when two men who request a ransom of ten thousand dollars have kidnapped one of Trampy's clients. The diabolical mind behind the kidnapping is a mysterious individual dressed in black: he calls himself Mister Smith and is the most unusual enemy that Zagor has ever faced!
