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.
(..) Once trusted by this Council... ...charged with maintaining the defense of the planet Krypton itself. Chief Architect of this intended revolution and author of this insidious plot... ...to establish a new order amongst us... ...with himself as absolute ruler. You have heard the evidence. (..)1978 Superman
(..) Then you're both sad? Yes. Maybe she'll feel so guilty, she'll never make me celebrate the holidays again. So your evil plot here is to buy your girlfriend a present? That's right. So stay on my good side, or I'll get you a little something, too. Okay, here's the plan. (..)2014 TvShow: The Big Bang Theory Title: The Clean Room Infiltration Season: 8 Episode 11
(..) counteracted the biotoxins. Residents of Lower Manhattan can rest peacefully... ...knowing that the alleged mastermind... ...of this terror plot, Dr. Curtis Connors, is behind bars. ...on the street for a report in Lower Manhattan. Sweetheart, it's all right. It's all right. (..)2012 The Amazing Spider-Man