Harry "El Caliente" and Billy "El Frío" (Jorge Martínez and Ricardo Espalter) are two successful detectives, hired directly from the United States to solve a series of gold robberies from coaches owned by the Argentine Gold Mining Company. They are "Spaghetti Western" type cowboys, who are helped by four mysterious riders dressed in white overcoats and white hats (Enrique Almada, Eduardo D'Angelo, Andrés Redondo and Berugo Carámbula). The four riders always appear just to help the two detectives, in the role of "guardian angels".