Complex sentence: Hunter, who had thought he was playing a detective, was upset to learn that his role was that of a criminal, although he remained in the role for the entire Broadway run before joining a touring company for the play.
Split into simpler sentences: Hunter, who had thought he was playing a detective, was upset to learn that his role was that of a criminal. However, he remained in the role for the entire Broadway run before joining a touring company for the play.