Story before legion in a nutshell?

Hi, as a new WoW player (4 weeks in) I have not had the time or luxury to really understand or catch-up with the lore as I've been power leveling to have a max level 100 character to enjoy the expansion with my friends.

Question I have is can someone put in a nutshell the story line that is relevant to the legion expansion. I have a basic understanding of the Titans/Sargarus, I have a basic idea about illidan being the brother of malfurion and fighting to impress that chick. But beyond that I'm not sure where to start to understand the rest or what order things happen. Is there a written short story/guide? I'm at work so cannot watch YouTube links etc