Looks like chapter 24 is called Endgame. I guess this answers my own question. Just one damn crossword puzzle to go!

I'm at 17 so far.

I'm stuck on 16... doesn't seem to be doing anything after I shared the folder :/

Hit the "Repair Dropquest Folder" link on your current chapter's page to fix that.

I had the same issue after the chapter where you invite an email to share a folder. I invited it to the Dropquest folder, which I guess was a bad idea!