From the introduction:
One of the criticisms Doomstones Campaign gets is that there’s no real reason for PCs to get involved with it. There’s nothing driving them to investigate the clues they find or to look for the Crystals, and they don’t really know what’s going on or why. It’s also difficult to bring in your own player characters, rather than using the pre-generated ones in the books. This brand new introduction to the campaign is designed to solve those problems in an engrossing and atmosphric adventure.
This short adventure is in two parts, each with a different purpose. The first part assumes that you haven’t started running Doomstones Campaign, and is designed to get your characters into the Yetzin Valley, where most of the campaign takes place. The second part introduces some of the background to the campaign itself, and gives the adventurers a little idea of what is going on and why they should risk their lives to recover the four Crystals.
This short adventure is intended as a "hook" introduction to Doomstones Campaign; these adventures are not necessarily needed, however, as this could (theoretically) be used as a standalone adventure. Note this is not an official part of the series.