Meet my Hatchet of Death (or, some other colorful description RC Lewis and I come up with at any given moment). This is how I edit myself, it is how I edit others. If you think you want to play with me and my hatchet, shoot us an email.
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.
If you're looking for query advice, but are slightly intimidated by my claws, blade, or just my rolling googly-eyes, check out the query critique boards over at AgentQueryConnect. This is where I got my start, with advice from people smarter than me. Don't be afraid to ask for help with the most critical first step of your writing journey - the query. My comments appear in green.
After four years training to be a warrior, Princess Raylene returns to her homeland to find that all is not well: burglaries are on the rise, people are disappearing, and officials are being murdered. Her grandmother, the empress, denies these signs of danger. But when her father meets with a fatal accident, Raylene is willing to risk her throne to uncover the truth. This looks great right off the bat. My only suggestion here would be that it might not hurt to mention why a Princess would be training to be a warrior (is this typical? Or is an exception being made for her?) But that's a small tweak, otherwise this is a strong start.
Raylene discovers the involvement at what level? Is he burglarizing, or killing? of a rebel named Lord Lancelot. He’s recruiting criminals and deadly monsters into his army. Many high-ranking officials are secretly lending him their support. Why? In order to identify the Lord Okay so "Lancelot" is his code name or something? Because since we know his name I assume he's been identified., Raylene resorts to torturing whosoever she suspects. Maybe a little bit here about how Raylene feels about torturing people - I'm assuming she's not so thrilled, but a little more on that point to make it a sympathetic choice. Furious with Raylene’s incessant is it actually incessant or is torture her first step outside the law? Because that's the first we hear of her toeing the line law-breaking, the empress sends her to prison.
Now Raylene must find a way not only to catch the rebel leader but also to get herself out of imprisonment. If she fails to stop the uprising it’ll be the end of the royal family that has ruled for centuries.
UPRISING, a YA fantasy complete at 84,000 words, has series potential. I believe it will appeal to readers of Kristin Cashore’s GRACELING and Ellen Oh’s PROPHECY.
For the most part this is a pretty strong query, except for the notes above. I would work on perhaps a little more world building in the query - you say there are deadly monsters in this rebel army, but that one word is the only hint of any kind of supernatural or high fantasy elements in the query. If the book has magic, monsters, demons, dragons, etc. get those pertinent world building facts into the query.