this book is a coming-of-age story with a fantasy twist. its central character is alastair, a boy who is good at keeping secrets. it is also about his "best friend" charlie, a video-game obsessed pain in the ass, and fiona loomis, a girl who has been to another world. 
 alstair is more or less a loner. he hangs out with charlie, but it is more out of convenience and habit than anything else. fiona is a girl he used to play with when they were little, but as they got older, their lives diverged. 
 She was unknowable in the way that all girls are unknowable, but also in her own way. 
 so when she shows up on his doorstep with a box containing a tape recorder and a command to "pen her biography," alastair is caught off guard, but the more he hears, the more intrigued he becomes. 
 fiona claims she needs a witness with an imagination, and she begins to tell him the story of aquavania, the magical world she can enter through a portal in her basement. alastair is skeptical, but transfixed and she tells him about the creatures and landscapes of aquavania, where anything that can be imagined can be created. however, there is a dark side to aquavania, and lately, friends that she has encountered there have gone missing, and have also gone missing in the real world. fiona attributes this to the riverman, a shadowy figure who is rumored to steal the souls of children who have entered aquavania. 
 alastair listens to her, and records her story, but begins to believe she is trying to tell him something altogether different, and his imagination, which fiona had hoped would allow him to believe her story, goes in the other direction, trying to find real-world situations and explanations for the story of kidnapping and abuse she is sharing. 
 and even though he is a boy who keeps secrets, at some point, the secrets become more dangerous than the truth. 
 it's a really strong book about that delicate cusp between growing up out of the power of childhood fantasies and into the reality of the adulthood and the mistakes and misperceptions that haunt that liminal space. 
 i see this listed as middle grade in some places, but i would hesitate to give this to anyone under 13, honestly. and, again - i know nothing about kids, but there's a bunch of violence, and one particularly icky scene involving a cat, sexual innuendos, a little drinking and drugs.. nothing major, but i mostly think that the message here is a little too psychologically sophisticated to spring on an eight-year-old. i feel like older teens would recognize something in the character's experiences that a younger reader would have no context for. yet. 
 a for-real spoiler, so just don't 
 (view spoiler)[because i think the most powerful emotional takeaway here is that alastair thought he had it all figured out with this sort of deductive psychology - that there was no aquavania, and he was trying so hard to think about things in an adult way, and it is just devastating to realize that it was true all along. and while i loved that narrative possibility; that fiona was going through something very serious and using this fantasy realm to articulate it to him, it was even more shattering to realize that he had still had access to the child's world of fantasy and he chose the adult world and he muddled it. there's kind of a double loss of innocence in that. and i don't think that would hit an eight-year-old as hard as it would hit an older reader - one who has already firmly set aside the realm of childhood. there's a deeper sorrow and nostalgia payoff for a reader who has just recently struggled so hard to act like/be treated like an adult only to learn that the magic of childhood does exist. (hide spoiler)] 
 definitely one to check out, but wait 'til you're older.