They are accused of 'plotting' the assassination of the prime minister. = They are accused of 'plotting' to assassinate the prime minister.
As the 'plot' unfolds [=as the story continues; as things happen in the novel, movie, etc.], we learn more about the hero's family.
He is a master of 'plot' [=he is very good at thinking of interesting stories], but his characters are not realistic.
(..) I'm Francesca's long-lost son! Right. Could you sign? No! No way! I'm not signing that! I don't think that will affect the plot of the show. How can they do this to me? All right, I'm just gonna go. Sorry. Well, it wasn't that many guys. If you consider how many guys (..)1996 TvShow: Friends Title: The One Where Dr. Ramoray Dies Season: 2 Episode 18