Sometimes writers overthink their queries. I know I've been guilty of doing it. Yes, you want the right tone, but start with the facts and build from there.
I strongly suggest starting with the journalististic who, what, where, when and why. Here's an example from an actually query letter that garnered requests.
"Only something seriously nasty would drag Dr. Bebe Zachary (Who) home to San Francisco (Where). If her grandmother’s accidental overdose weren’t bad enough, her cousins have filed to overturn Grandma Petrov’s will and lost the coven’s Book of Shadows in the process (Why). The only way to get the politically incriminating Book back is to buy the wardrobe it’s hidden in at the estate auction (Why). Except she’s outbid by the only thing more infuriating than her idiotic cousins--a vampire (What). And not just any vampire, but the coven master of the western United States, Caesar Augustine (Who)."
Notice the only question I don't answer is when. That queston is answered through circumstantial evidence by stating the U.S. exists and Bebe is a doctor. Without additional information, most people will assume the manuscript is contemporary, which it is.
If you need other opinions on your query, Rick Daley's The Public Query Slushpile is a marvelous place to get feedback from peers in a safe environment.
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