I do not often give 5 stars to a book, but this one impressed me.
Daniel presents his material in nine interlinked brief stories. Often, the links between the stories are embedded in one fictional "layer", and we encounter the main character of one story as a side character in another, and vice versa. This device, in the way I read the novel, created an effect as if I (the reader) was empowered to look at an event, or the personality of a character, in two ways. When I encountered a character as the protagonist of its chapter, I inhabited the character's mind from the inside. When, later on, I inhabited the thoughts of a different protagonist, in a different chapter, I observed the protagonist of an earlier chapter with external eyes. Daniel constantly swapped internal and external views of characters in the novel, and I ended up asking myself which view reflected "reality"? Is it the view a character has of himself? Or is it the view others have of him? And of course, we have not seen these flips in perspective for the first time - Daniel loves thinking about internal and external realities, indeed, he explored this theme also in Mahler's Zeit. But I don't think Daniel achieved a mastery of the level shown in Ruhm in his earlier work, so this technique is spot on here.
This would be impressive enough, in my view, but I have only scratched the surface. Often, the links are of a more fundamental, deeper kind. In one story, the main character starts interacting with the story's narrator. This is amusing and a joy to read, but it also cleverly connects two, normally separate, layers of fiction. A narrator stands above the characters in a story, it does not normally interact with them.
Fair enough. But in a later story this narrator is identified as Leo, a writer and protagonist in the first story. And this is where it is starting to get truly weird. A fictional character in the first story is the narrator of a later story. Therefore, that later story is fiction of fiction, it is, if you forgive me the jargon, metafiction. Indeed, in that story, we encounter somebody called Lara in a telephone conversation which she conducts from San Francisco, in America (why the location is important will become clear in a moment). Lara is a character who we know to be Leo's creation in one of his novels. So the fictional Leo writes a story (from the point of view of the reader, this story has revealed itself as a "metastory" on finishing Daniel's novel) in which he has his (meta-fictional) protagonist interact with another one of his (meta-fictional) characters, taken from a different meta-fictional novel.
And if that was not confusing enough, in the final chapter we encounter Leo again. In this chapter, however, he meets Lara, his own fictional creation, as she emerges from a tent, the scene set in an African country. Leo's girlfriend, who is with him, is surprised, as she thought Lara was in the US. So now we have the fictional Leo interact with his own fictional creation, and his fictional girlfriend referring to the fictional location that fictional character (Lara in the US) was identified to inhabit in a completely different chapter of Daniel's novel. So who's real now? Or better, who's fictional, and who is meta-fictional? Leo's fictional, and Lara is meta-fictional. But if that is so, how can Leo interact with her - he also needs to be meta-fictional. Which would be an issue, as in that case the fictional story in which his character interacts with him would be one further fictional layer removed, and become meta-square-fictional. And is his girlfriend fictional (as she interacts with Leo) or meta-fictional (as she interacts with Lara)? Who knows - she's both, really, she's in a state of superposition between fiction and meta-fiction.
This is a novel in which fictional and meta-fictional layers blend, fold in on themselves, separate and re-join like the neck of a four-dimensional Klein bottle. This is a masterful novel that plays with analogues of reality and fiction within a work of literature, and in doing so, reflects on the nature of reality itself. The only, minor, criticism that I have is that Daniel drops a needlessly heavy hint that this is what his novel is about in the final chapter. Without Leo's blunt reference to "stories within stories within stories" (p233 in my edition), Daniel's caleidoscopic journey through the ephemeral nature of reality would have been pretty much perfect.