When Duel died suddenly on December 31, 1971 (reportedly of a self-inflicted gunshot), an attempt was made to continue the series with another actor, Roger Davis, in the role of Heyes. The series continued for another seventeen episodes, but never regained its popularity after the loss of Duel. Davis first voiced the intro theme, which explained the storyline. When he was hired to play Heyes/Smith, Ralph Story assumed the intro narration. In the final season the intro referred to Heyes and Curry as "Kansas cousins". Two episodes that season also made reference to them as cousins.





