The box art says it is an expansion and requires the base game. It doesn't seem to include the main boards, voting tokens, tracking tokens (for mission success/failure), mission and group voting round trackers, or base game rules. Sounds like an expansion to me.
Okay well I have a really old version of the base game that already includes the Plot Thickens cards. So the only thing I'd be getting is the Rogue role cards? Or are the Plot Thickens cards updated and improved?