It's about a green capitalist who works with the CIA and a treasonous general to overthrow the left wing government of Bolivia in exchange for access to resources. It's fucking crazy. As a bonus, they even mention that the general's whole goal is to keep the gov't from raising the minimum wage to $1.
Naturally, at the end the bad actors in the CIA get fired and everything is put right... But God damn, up until that nonsense it's an incredibly perceptive film
As a piece of cinema, it's kinda confused. The plot jumps around. The acting isn't nearly as good as Casino Royale. Bond's character digresses from the genuinely interesting emotionally complex character who does spy shit in his original film to Doing My Best Pierce Brosnan Impression.
Still not as bad as Spectre or Skyfall. But Casino Royale set the bar at "Good Spy Movie with Action Bits" and Quantum lowered it to "Better than Average Bond Movie with decent politics".