TL;DR: Stuff Your Kindle Day is live on May 13-16. Into the Darkness , hosted by the Indie Author Collective, is offering free dark romance and mafia romance books for your Kindle or Kobo . Another Stuff Your Kindle Day is going live this week. We've been blessed by a number of these free giveaways this year, covering everything from mystery and crime to sports fiction. The latest event offers something a little different, with dark romance and mafia romance books on the menu. Into the Darkness , hosted by the Indie Author Collective, is offering participants the chance to download dark romance and mafia romance books without spending anything. And better yet, everything that you download is yours to keep forever. Looking to make the most of the latest Stuff Your Kindle Day ? We've lined up everything you need to know about this popular event. When is Stuff Your Kindle Day? Into the Darkness takes place on May 13-16. Unlike a lot of these giveaways, you've got four whole days to stock up on reading material.…