Meet the BBC 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. 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 yellow.
Sometimes a virus is more than just a medical problem, it's a political weapon. Here's the thing, this hook feels like it's for a techno-thriller or a medical mystery. Your genre is dystopian and that needs to be clear from the beginning. When I read your hook, my original reaction was, "Meh... OK but let's spice it up," then I was immediately confused once we got to princes and thrones, because I was already geared for a contemporary political thriller.
On the verge of his coronation, Prince Anton gave up the throne, eliminate some of these commas, if you read it aloud and actually give the correct pauses for the commas you'll feel the slow pace and set out to eradicate a devastating virus that causes its victims to slowly bleed to death. For over a hundred years, his family's power has come from their immunity; the only treatment is derived from their blood, but Anton's quest threatens their hold on the empire. OK that's actually very interesting - they've got power because they are the living immunity. So... what's his motivation here?
In the imperial capitol, Anton flaunts a fabricated playboy persona in order to shield what is most dear to him from public judgement. Abroad, Anton has cleared nation after nation of the virus. But his most difficult task lies ahead; eradicating the virus in the homeland of his estranged wife, Tia, a radiant beauty who hides a deep sorrow behind her delusional sense of optimism. The writing here is fine, but I'm going to raise some questions. It seems like if he were voluntarily giving up the throne and going out to all these countries to use his own blood to make people immune, which in turn will undermine his family's power - how the heck does anyone buy the playboy persona? He sounds more like Gandhi. Also, I assume from the mention of Tia in this para that she is "what is most dear to him." But why would the public judge him for loving his wife?
Anton and his forces he has forces? Why? If he's just going around like a reverse bloodmobile why does he needs them? return to the distant war-torn island where a tragic secret gave rise to his quest against the virus. OK - so here you're *toying* with answering my question from para one - Why is Anton doing this? Because of the tragic secret? Not sure you can float "tragic secret" out under an agent's nose in a query and expect them to bite at that for the motivation that moves the whole plot. From the moment they arrive their well practiced routine is thrown into chaos. Survival instincts have bred strange alliances. Tia is both hated by her countrymen for her past connection to Anton, and an integral part of the militias fighting Anton for power. Awkward sentence here before this comment, the "both hated..." implies that there's a "and loved for..." coming up, but you don't give us that. Instead you say she's an integral part of the militia fighting Anton... but the sentence isn't quite working. The public, desperate for a cure, become pawns in a violent clash of ideologies. Confused on what ideologies are clashing here? Why are they fighting Anton if he wants to give them his blood to cure everyone? If they don't want him to have power anymore, they would let him do EXACTLY what he plans to do by giving people the immunity, thus undermining his power.
As time runs out Anton's motivations are revealed to be not nearly as altruistic as the public's been led to believe. Again - so if the public has been led to believe he's a good guy, why is the army fighting him? He faces a choice between his own morals, and his love for Tia, only one of which can survive. How do his morals come into this? And how are his motivations not altruistic? You're going to have to come clean in the query about what his motivation is, and the "tragic secret," otherwise you're just floating this out there asking the agent to trust that you know what you're doing. And they see hundreds of queries a day from people who *don't* know what they're doing plotwise, so don't give them any reason to dismiss you as one of them.
WHAT THE WATER GAVE US is a dystopian novel complete at 99,000 words.
Ending thoughts - love the title, and the writing here is solid. You just need to get the actual motivations of your main character "out there" and not shroud it in secrecy.