When sixteen-year-old Olivia returns to Caldwell Beach, she’s
determined to pick up where she left off six years ago. This is awkward and sounds inappropriate to her age. A sixteen year old girl does not want to pick up where she left off as a ten year old girl. Does this mean she wants to play with Barbies? It's the wrong choice of words She’ll reconnect with her old life Again, here: 40 year olds reconnect with their old lives, sixteen year olds don't reconnect with their ten year old lives. I think I understand what you mean it's just how you're saying it is with an expression reserved for older people. Sounds like she's eager to meet her old friends, see how they've changed, etc. Just write something like that (does she have a best friend she's curious about?), and if she’s lucky, overcome her fear of the water.I like this goal of overcoming her fear. But if it is a goal of hers then 'luck' has nothing to do with it. But things have changed in the once-sleepy town--Olivia’s childhood friends have become reckless, vandalizing partiers, You are making it sound like the whole town has changed when more often the reality is that there have always been reckless vandalizing teens and Olivia was just oblivious to them (as a ten year old). My suggestion to you would be to make it more personal to her. She has this image of what she's coming back to (get specific: she can't wait to go to Bill's ice cream shop, or to play tether ball with Julie (those are stupid examples but hopefully my point is clear)) but her friends have grown up now and become reckless vandals. It's not about the town. It's about Olivia's expectation and the reality and when Olivia discovers a mutilated squirrel carcass, she learns that there’s a serial animal killer in town. I agree with Rosiesky one animal carcass does not a serial killer make.
Freaked out but determined to enjoy the summer, Olivia
tries to distract herself with West, her ex-best friend’s drop-dead drop-dead adds nothing to this but cliche gorgeous brother. But the closer Olivia gets to West, you're hinting that these two are related but I don't know why or the significance. Does she think he's the culprit? Or involved somehow? Put us in her head here. Right now, I'm thinking: So West is the problem? Then dump him. the more strange things start happening in her life. There’s the footsteps following her home, the tapping on her bedroom window, and the animal bodies left conveniently"conveniently" sounds awkward. They're deliberately placed in her path, which makes it sound more ominous. There's nothing convenient about an animal carcass, unless you're a butcher. Now if she'd stumbled across a vacuum cleaner after her mother told her to vacuum the rug, that would be "convenient" for her to find. Olivia swears someone is messing with her head, you're lowering the stakes here. Someone messing with her head is inconvenient and annoying but it's not worthy of a psychological thriller. Up the stakes. Olivia calls the cops, tells her parents, but no one believes her. Now she's carrying a pocket knife for self-defense . Now she's holing up in her room with the shades drawn, that summer tan fading into a pale ghostly paranoia, . Get specific. but without any evidence, everyone thinks she’s imagining it. When not even West say this out loud, it'll probably plunge you straight into a British accent. "When West doesn't believe her" believes Olivia, she knows she has to do this herself. She'll find whoever is harassing her... if she can prove that the stalker is even real.
So Olivia returns to a beach town that I assume she loved when she was ten. But it also sounds like it's just a vacation place. Is this her old hometown? Is it something she's idealized ever since she left it? It matters because if it's just a beach town she used to visit then the revelations of her friends being different is not that revelatory. In fact, it's kind of expected. So she returns to the beach town to find her friends are now hoodlums and somebody likes to kill squirrels. It's disconcerting but not heading into thriller territory. Then she falls for some boy and someone else starts stalking her. And her stalker may not be real. That's a lot of disconnected information you drop in the end. It starts with a girl wanting to have a great summer at the beach to a girl who may be going crazy because nobody else can see the person stalking her.
I think you need more connections to get to that place.
You've written a psychological thriller (according to the subject of this post) but there's little here to hint to either the psychological or the thriller. There's no feeling of danger in this story. There's no hint that she could be hallucinating this even though everyone else seems to think so. Does she wonder if she is hallucinating it?
Who is Olivia?
What does she want?
What obstacles get in her way?
What must she sacrifice?
Not sure if she's in any real danger in the story because it's not apparent in the query. I get that the footsteps and knocking is a little scary but it's not enough. I'm assuming you've ratcheted up the tension as the story goes on and you need to include that in here. You need to show us what's at stake for Olivia and how finding out could be life-changing. And if the climax doesn't involve something with her fear of water then you've set me up for disappointment and you should remove that sentence from the query.
I could say more but I've probably said too much. I'll check back for any revisions you might have.