Also, I'd like to point out that you'd only have 5 plot cards the entire game if you were playing with 5-6 players, as you only draw one at a time. You'd have 10 in a 7-8 player game and 15 in a 9-10 player (drawing 2 or 3 at a time, respectively).
Whoops. I didn't consider that. I wonder if I've always gotten that wrong, or have only played with the plot cards with 5-6 players...