Dear (Agent Name),
Daisy Flint couldn’t prevent her twin sister’s death; not the first time, not the second time, nor the dozen times after that. Hazel Flint is dying, over and over again. Daisy is stuck in a time-loop, forced to repeat the day her sister dies. But she’s not worrying about how she’ll get to the next day; not before she finds a way to save her sister’s life.
Okay your opening sentence is seriously cool. The issue for me is your use of verb tenses. The first sentence is past tense, which throws me for the rest of the paragraph, which is present tense. And this might just be a style preference, but the -ing verb usage feel passive. I would have said "Hazel Flint dies over and over again....But she doesn't worry about how..." The last sentence confuses me a little. Daisy does not worry about how she'll get to the next day....must she first save her sister's life before she can move on?
After countless attempts at changing Hazel’s path (fate?), Daisy is running out of things to try. She’s memorized the day, and everyone’s routine, but no matter how much she tweaks it, Hazel always meets the same end, dead in the schoolyard by sundown.
Again, your preference to use -ing verbs feels passive/unpolished to me. For example, I would have said: After countless failed attempts to change Hazel's fate, Daisy has run out of things to try. The last sentence is the show of your telling first sentence. This entire bit can be condensed to: No matter how Daisy tweaks everyone's routine throughout Hazel's day, her sister is always dead in the schoolyard by sundown. Actually, this should be combined with the first paragraph for one solid intro:
Daisy Flint could not prevent her sister's death, not the first time, not the second time, nor the dozen times after that. Hazel Flint dies over and over again while Daisy is stuck in a time-loop forced to relive her sister's death. No matter how Daisy tweaks everyone's routine throughout Hazel's day, her sister is always dead in the schoolyard by sundown. Though Daisy is caught and powerless, she does not worry about how she'll get to the next day. Not before she saves her sister's life.
Okay, this is not polished, but you get my meaning :)
But as another one of Daisy’s plan fails, she notices something that isn’t on the script. Someone is in a different position; a boy is moving outside the boundaries of the time-loop, like her, and he might be the answer she’s been waiting for.
"Daisy's plan fails" should be "Daisy's plans fails." While grammatically correct, it reads unpolished, and I would recommend to revise it completely. Like, After another failure, Daisy notices something...
"Someone in a different position" is telling which "a boy is moving outside the boundaries" is showing. Suggestion to just say something like, "After another failure, Daisy notices a boy move beyond the boundaries of the time-loop..." - Note I also got rid of the is -ing verb.
The boy is Miles Novak, Hazel’s secret friend. He claims the time-loop was his doing, a forbidden spell cast in desperation
with the hope he could to change Hazel’s fate. He opens Daisy’s eyes to a world of different rules, a world of magic; a world Hazel is involved (trapped?) in.
Why is he a "secret" friend?
"He claims the time-loop was his doing" sounds unpolished, and I'd recommend something simple like, "He created the time-loop."
"Opens Daisy's eyes" is a little cliche.
With secret friends, and a strange cult masking as a school chess club, Hazel’s lies come to light. The revelations are like a knife in the gut to Daisy,
who’s always shared every secret who shares everything with her twin, but and even though it hurts, it might just be the twist she needs to put an end to this nightmare.
The chess club reference feels random, and I don't know how it connects to anything prior. Recommend removing it.
"A knife in the gut" also sounds cliche...not sure.
HAZEL FLINT IS DYING is a YA Contemporary Fantasy novel completed at 98,000 words. It will appeal to readers of Melissa Albert’s The Hazel Wood, and Karen M. McManus’s One Of Us Is Lying.
Thank you for your time and consideration,
Thanks in advance!