It's just one big mission for Mankind Divided, but honestly, it's pretty good. The story is just an excuse for a cool bank heist mission. The mission itself reuses a lot of assets you see through MD but the level design is above and beyond anything you see in the base game. There's a lot to find, there are some gimmicks that make stealthing more challenging, and there is a reason to replay and try a different approach. Definitely a good DLC worth playing though at least once.