Dear Ms/r (Agent Name)
I would recommend you start your query here. With the CHARACTER. The protagonist is the most important character in any story, and the concept of CHARACTER is the most important aspect of almost every great query letter I've ever seen (there are exceptions, but it's rare). Give us a person to relate to, who we can sympathize with, right away. Otherwise, it doesn't matter how cool whatever happens is, because we won't care. Kelsey’s visions of a perfect Senior year go up in flames the night her boyfriend Dave crashes his car. This isn't bad, but this is all plot, or maybe even backstory. Try to introduce more about what kind of person Kelsey is first. Even his daring rescue of one of the passengers can’t erase the fact that he’d been drinking and driving. Was the care on fire, like literally up in flames? If so, say that. Otherwise it's kind of hard to picture rescuing someone from a car accident. With Dave banished to an aunt’s farm for the summer, Kelsey’s stuck wishing she had warned him of her eerie premonition. Now this I like. I hope you explain more later.
Kelsey knows Dave is facing lifelong guilt and strict terms of probation when they return to school in the fall. But she wishes he hadn’t appointed himself personal protector to Calvin, left disfigured and an amputee
Calvin’s art is beautiful and disturbing: a comic book series depicting himself as an Angel of Death with the ability to swap souls, and Dave as his arch-nemesis. Accusing a brain-damaged accident victim of a supernatural revenge plot won’t
Since the day of the accident, Calvin’s been practicing the superpowers from his stories, with the goal of swapping his broken life for Dave’s life of wealth and privilege. But he can feel Kelsey closing in on him, and she’s getting too close to the truth. Making her part of his revenge is a surefire way to stop her, and when Calvin successfully takes over Kelsey’s body, his story becomes horrifyingly real. Wait, what? Now it sounds like this is being told from Calvin's point of view. Is that on purpose? I do see below that the manuscript alternates POVs, but don't do that in the query. Or at least, not like this. Whichever character is more important, stick to that POV. You can certainly describe what Calvin goes through, but it needs to be from Kelsey's POV, otherwise it gets confusing.
Now, that being said, plot-wise this is pretty cool. This query is too long at this point (the "meat" is 350 words, and you should try to keep that part under 250 if you can) but if you can figure out a way to convey this info more quickly, you'd be in good shape.
Now there’s more than Kelsey’s reputation at stake. Dave’s worst enemy is using her body to get his ultimate revenge, and Kelsey is trapped inside Calvin’s damaged body, struggling to communicate. Instead of trying to get back together with Dave, Kelsey has to convince him that the girl he thinks he’s falling for is a deadly threat. To stop Calvin, she’s going to need to overcome his supernatural abilities and uncover the truth about what really happened the night of the accident. This is kind of frustrating, because while it's confusing to read and consider, it also sounds like an incredibly cool story. Hopefully you can think of a way to clarify this a bit.
CREEPY BOY is an 85,000 word Contemporary Young Adult novel with supernatural elements. It’s told in the alternating POV of Kelsey and Calvin, with plenty of twists and turns that keep the reader guessing.
Okay, so in summary, this query does need a bit of work, but it's clear you have an awesome story to tell, so that's helpful.
Not every query letter has to be the same, of course, but in general the ones that work focus on a few basic elements that help them stand out.
CHARACTER. As I said above, nothing in STORY is more important than CHARACTER, and therefore obviously nothing is more important in a query. We know nothing about Kelsey. What kind of person is she? How old is she? Is she a cheerleader? A stoner? A punk? A goth? Obviously you don't want to shoehorn her into some stereotype, but there's a reason that archetypes work, and it can help the reader get a better sense of who is she before her story starts and therefore care about whether she succeeds when it comes to ...
CONFLICT. You could also just say plot, but CONFLICT is the second most important thing in STORY, and so, yeah you get it. You actually have a pretty excellent sense of the conflict set up here. Dave wounds Calvin, Calvin wants revenge, Calvin has powers, so Calvin switches bodies with Dave's girlfriend Kelsey. I mean, there's more to it than that, but that's basically it. You just need to figure out a way to convey that in less than 250 words. You've got the threads here, you just need to expose them a bit more succinctly.
CHOICE. This isn't really required, and it's far less important than the two elements before it, but good query letters often end of what's called a sadistic choice (that's a TVTropes link, you've been warned), the kind of thing that it's nearly impossible for a character to decide about, and therefore makes the reader (hopefully the agent's assistant) have no choice but to want to read the pages.
Those are the three main elements, but there are a couple of other common things like an inciting incident which turns an innocent world into an exciting new one (I get the feeling that is your car accident, unless that's backstory), and you've got that pretty clear here, but basically what you want to try to do is come up with something relatively similar to this:
Opening paragraph introduces very sympathetic protagonist, and we readers care about her right away and want her to win. Then once we know who she is, you can finish the paragraph by telling us what starts to happen to her, or in other words what the inciting incident is.
Second paragraph covers the main conflict. Introduce the antagonist here, and explain what they want and why/how it goes against what the protagonist wants. Be specific. Nothing damages a decent query more than vagueness.
Final paragraph (this is of the "meat" part of the query, your "housekeeping/bio/personalization" section can be another paragraph or two, but keep the "meat" to 250 words or less if you can) covers the sadistic choice, or at least makes clear what the protagonist must accomplish in order to succeed or win or at least survive the conflict.
All in all, you've got all the elements here. You just need to introduce Kelsey as a character more, and sooner, and then you need to pare down your description of the conflict so that it packs much more punch. The premise of this story is obviously really cool, it's just muddied by the confusing way it's described.
What do you think? Please share your thoughts and feedback below.