The success of the 1971 telefilm "Duel" signaled the rise of movies produced specifically for television. Some featured a hero or heroine whose life was in jeopardy, while others were pilots for proposed TV series to be picked up by a network. (Some sold; many did not.) Still others centered on the destructiveness of a certain disease, whether medical or social. "Roots", a multi-part miniseries that ran on a number of consecutive nights in early 1977, proved to be a huge hit in the ratings and thus paved the way for others of its kind like "Shogun" and "The Thorn Birds".