The author states in the acknowledgements that this book was inspired by her love of horror films, with Scream being referenced many times in particular. (Good logic, because Sidney is one of the best final girls in horror history.) However, as a lover of horror films myself, I cannot possibly recommend this book to anyone, not even as an intro to the genre.
Most of this story's first half is focused on the main character's role in this immersion experience she's working at, describing her responsibilities of being the "final girl" and dealing with an absent boss/truant coworkers. Sure, she describes seeing strange things/hearing weird noises that scare her, but either she waves them off as "the camp getting to her," or someone else will provide a different logic that she seems to accept.
The plots were easily broadcast, especially if you have knowledge of horror movie tropes. The fact that her boss, who is conveniently absent most of the time (and has given weird/conflicting information about things at the camp) being involved in the killings at the camp was something that is super obvious. The "nice guy" at camp that is close to the final girl also being involved with the current killings happening was also pretty easy to spot. (The only thing that might not have been TOO obvious was that they were related, but once that plot point was revealed, it made more sense.)
The cult also felt super pointless. Owls were being used as a thematic (and/or threatening) imagery throughout, and there was a line of a Secret Order being referenced by the crazy woman with the shotgun, but they really came into the story in the last quarter of the book. After that, the motivation of the main character became "stop obvious bad cult from killing everyone at the camp so that they can't complete their ritual," which really felt out of left field given what we'd been reading about so far. (Really gave me Cult of Thorn from Halloween vibes, which is NOT the feeling you want to have, if you've seen those awful movies.)
And the whole "use the incantation to bring my dead girlfriend back after a whole year of being dead" thing was just...I don't even know what to think. Did it bring Charity back as a normal girl? Was she decayed from being in the water for a whole year? The world may never know, since it just abruptly ends.
I wanted better from this book, but it fell flat so fast. I love reading YA, but this was something that made me push to finish it. I honestly should have just DNF'ed it.
Avoid this book. There's better horror books out there, but this isn't one of them.