We all know the first line of a query is your "hook." I call the last line the "sinker." You want it to punch them in the face, in a nice, friendly kind of way that makes them unable to forget you after having read the 300 other queries in their inbox. Also, at the end, I'm going to tell you what I think your story is about, based on your query. I know how hard it is to get your ideas across succinctly, and how easy it is for your author's brain to fill in the blanks and not see the gaping holes that the average reader may very well fall into.
Also, for my brave Saturday Slash volunteers I will gladly do follow-up slashes (each more kindly than the next) on your query if you post them on the Query Critique board over on AgentQuery Connect. You'll get advice from me, and also people who are smarter than me. If you do post on AQ, be sure to follow the guidelines and let me know you posted so that I can follow up!
And now for our next brave soul. For clarity, my comments are in purple.
Having a ghost attached to you isn’t exactly what sixteen year old hyphenate age, Bailey Green, don't need the commas around your MC's name would call ideal. The victim of a drowning––Hannah Melbrooke has been haunting Bailey for three years with no explanation. Haunting how? Is she creepy? Friendly? Due to Hannah’s extended stay, Bailey is forced to come to terms with the ghost who is incapable of leaving the confines of her bedroom; a semi-colon is used to join clauses that can stand on their own as sentences, which the second half of this can't due to an unknown force. You definitely need a stronger hook. So she's being haunted - so what? That's the premise of every ghost story. What makes yours unique? I think the answer is in the idea that the ghost is trapped in the bedroom, and the force that keeps here there, but it's the last thing you mention in your first para. Rework to get that front and center.
Bailey doesn’t realize that the more she believes in Hannah, the stronger she becomes, granting her freedom from her prison. When Hannah escapes into the outside world, Bailey’s haunting burden becomes an impossible secret to keep. With her social life invaded by the ghostly figure, Bailey begins to see Hannah for who she really is––a spiteful soul looking for vengeance. OK - I needed this sooner. I had no idea what their relationship was like. Having a ghost in your bedroom 24/7 and the MC's belief in her setting her free strikes me as more of a chummy paranormal sleepover than a vengeful spirit. Get that relationship out there. It's bad. It's evil. It's creepy-ass.
After a near-drowning inflicted by Hannah, their bond grows stronger as her brush with death breaks the seal between their worlds, leaving Bailey vulnerable for Hannah to extract her energy––the key to her resurrection. Awkward sentence. Bailey’s best friend, Eric Montgomery, becomes her true weakness, giving Hannah the crutch she needs to demand Bailey’s cooperation. Sounds like there's a romance buried in here, and that it's going to be exploited by bad girl Hannah. Capitalize on that in your query, and move the idea of a near-drowning and a death bond nearer to the meat of your query. It seems like it's the crux of the story, get it out there.
In DROWNING BAILEY, darkness surrounds the ghostly girl who seeks to consume Bailey’s life as her own––a life that should have been hers. Searching to uncover Hannah’s past, Bailey discovers the unexpected truth of their connection. With this new information, she hopes to find the answers that will put Hannah to rest, before she destroys both Bailey’s life and her soul. This last para sounds very much like a quick synop, not a closing hook for a query. But here's the thing - it's raising some elements that weren't addressed earlier that make me perk up and want to know what you're talking about. A life that should have been hers? Bailey researching Hannah's past? A dark connection?
There's more going on in this last para than the whole query. And Eric only gets a fleeting mention yet he seems to be a leverage point that the whole story could turn on. I think you need to figure out what the main element of the story itself is - entangled past lives? The threat of Hannah in the present? Bailey's weakness for Eric being the push point for the whole domino ride to come down?
It sounds like there's a lot going on in the story, that it would be fast paced and interesting. But the query itself is all over the place and doesn't seem focused, which is going to make an agent wonder if the same thing is wrong with the ms. Hammer down the *most* important elements and get that out there. You've got some great phrases and really cool ideas. I like the premise a lot, and I think the title is catchy, you just need to get a focus.