Still stunned by the emergence of the Great Rift and the rampage of the Tyranids, the inhabitants of Iyanden receive an unexpected message from a craftworld thought to be long lost. The artificial world of Zaysutra has emerged from the warp, where it had been hiding for millennia, and now, when its inhabitants want to make contact with their relatives, a small army of Aeldari, led by the spirit seer Iyanna and Yvraine, the herald of Ynnead, is sent to begin negotiations with them. Behind their desire to help, however, lies another motive - they are looking for the last sword of the Old Woman, which may be hiding behind an ancient web portal that is located in this artificial world. But how friendly will the mysterious Zaisutrans be, since they may also have their own plans?