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.
(..) 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