I'm not entirely sure as I haven't read it in detail. But generally, it might be about a world that has disappeared or changed significantly in some way.
Well, without having read it, it's hard to say precisely. However, from the title, it gives the impression that it could be centered around a world that has passed away or ceased to exist in its previous form. It might deal with themes such as loss, change, and the human struggle to adapt to a world that is no longer recognizable. Maybe it follows a character's quest to understand what led to the world being 'gone' and if there's any hope for renewal.