The Solitude of Prime Numbers tells the stories of Alice and Mattia - two misfits who are both haunted by childhood tragedies. Alice, whose sports trauma has left her forever handicapped, becomes obsessed with being beautiful and loved, and becomes anorexic. Mattia, after abandoning his twin sister in the park, turns into a complete introvert and starts cutting himself. He's also mathematically gifted, and at some point figures he and Alice are like prime 'twins' - numbers like 17 and 19, or 41 and 43, which can only be divided by one or themselves, and are one number apart (hence the title).This is one of those books that like to give a 'Stories are individual' message - the kind of open-ended but hopeful narratives, about common, but also broken people, who first need to find internal happiness before they can combat everything else. It's very heartfelt, with interesting characters and curious plotlines, which invest the reader until the very end.So why have I given this only three stars? Well, because honestly, this isn't really a story. It's the bare bones of a story. You can tell it's a debut because huge chunks of the novel are narrative, narrative, narrative. Scenes and characters that would merit plenty of limelight are rushed through for some unfathomable reason, as if the author was afraid that if the book was less than 300 pages long it would never get published.And, of course, then there is the whole character arcs, which are very much undeveloped. For example, we have Denis, the boy Mattia sits next to in high school and who is gay. His role in the story? To have a brief crush on Mattia, then to descend into a promiscuity and hit rock bottom, then find redemtion through love in the span of one chapter (you know, as gay people do), and then have one unsatisfactory discussion with Mattia which had nothing to do with their resolutions as characters. If only Denis was the only one. Nobody escapes this kind of treatment, not even the main characters.See, I think that The Solitude of Prime Numbers wants to be existentialist - to find redemption for oneself through internal happiness. The thing is that it doesn't succeed - Mattia and Alice just keep siralling into depression and alienation that by the time they hit rock bottom, the book is over, and instead of seeing them slowly crawl out of the pit they've dug themselves in, we see them trampoline up, which is not only unrealistic, it's really unsatsfactory.Mattia, for one, really pisses me off because his character arc is, essentially, him being pushed around until he decides that this is the path he wants. He is never proactive - not with Alice, not with his parents, not with the girl he meets in Norway - never. When he comes back to Italy to find that his parents and Alice have, surprise, surprise, changed, he just goes into a sulk and runs away again. What kind of resolution does he get? Is there anything that he has learned through this story? Anything at all? At least Alice takes some kind of decision about what to do with her life. Mattia, on the other hand, never does anything, when in fact, he has huge issues to deal with. He needs to confront his parents, especially his mother. He needs to adress these issues he has, because until he does, his life will continue to revolve around them. Yes, it's likely that it'll come crashing down around him, but that's the point of growing up - to break down the illusions, face the ugly truth, and then deal with it. Nothing ventured, nothing gained - both for the character and for the reader, who wants to see the story happening.