A lifeless gold prospector is found by Ken Parker around Bitter Creek, New Mexico. Having brought the body to the city, the young Marshal Arthur Comb organizes an expedition to look for his partner, who is rescued seriously injured. Meanwhile, among the citizens, instigated by Comb's father-in-law (to whom he owes a lot), the certainty is spreading that the two are victims of the Navajo, even if there is no evidence against the Indians. Only the Marshal and Ken will try, with great difficulty, to find out what the truth is.
Ken Parker, with his mestizo friend Nick, is in South Dakota, where he pays homage to the Yankton Indians and their leader, Mahto, also to learn more about a beautiful black wild horse that he wishes he could capture. At the same time, in one of the tents of the Indian village, the young Otomi is trying to convince Fiore di Luna's father to give her in marriage. When Ken returns among his other two occasional adventure companions, he will discover that young Sid is also suffering from heartaches.
