Season Four of Bonanza began on September 23, 1962 with what was intended to be a landmark episode. In "The First Born", Barry Coe plays Clay Stafford, a new ranchhand on the Ponderosa. Ordered to leave Virginia City after killing a man in self-defense (or so it seems), Clay reveals an astonishing secret: He is the son of Ben Cartwright's third wife Marie, and as such is the biological older brother of Ben's own son Joe. Although Ben and Joe take Clay at his word, the other Cartwright boys, Hoss and Adam are skeptical, and they intend to investigate Clay's strange story. As originally written by Judith and George W. George, "The First Born" was to have introduced Barry Coe as a new Bonanza costar. Reportedly, however, Coe's presence on the set caused friction among the series' established regular, and the notion of a "fifth Cartwright" was quietly dropped. ~ Hal Erickson, Rovi