The Quest

The main reason that shows are cancelled was and continues to be low viewer ratings on the network.  However it's more complicated than just that, as the causes for low ratings in the first place can range from poor writing, a bad time slot, or low interest in the show's concept.  In the case of the 1976 series The Quest it was the fact that the Western genre had fallen out of favour with audiences.

Created by Tracy Wynn son of character actor Keenan Wynn, The Quest told the story of two mismatched brothers who traveled across the country while searching for their long-lost younger sister.  Morgan "Two Persons" Beaudine, played by Kurt Russell, was captured by the Cheyenne at a young age, and was raised by them until freed by the United States Army.  After being reunited with his physician brother Quinton Beaudine, played by Tim Matheson, the two head into the wilderness on a quest for their sister Patricia, helping people along the way.

The show's concise writing, notable guest-stars, and the beautiful Arizona filming locations weren't enough to gain the show a foothold, especially since the NBC network chose to air it opposite the more popular Charlie's Angels.  After running from September until December 1976 it was cancelled despite having been nominated for a Prime Time Emmy Award for costume design.  Four of the fifteen produced episodes didn't make it to air.

The entire series was never released to home video, but the two-hour pilot episode was edited into a film format and released on DVD by Sony in 2011.  This DVD is rare and likely out of print.  The opening titles and clips from episodes are currently viewable on YouTube.