Mai became a thief to kill a murderer. She's waited patiently since childhood, training until she can take revenge on the thief who killed her parents.
Now, at twenty, Mai is practiced in the arts of thievery, stealth, and death. She believes she is ready until the blind and reclusive thief lord, Whisper, calls upon her for aid. The thieves' guild is being torn apart by a war between the gifted and the giftless. If she can help him settle matters, her reward will be power. Knowledge. If she can't, the guild will be destroyed, as will Mai's chances of finding vengeance.
Accepting Whisper's offer does not come without a price. She faces mortal danger as she is used against those she once thought friends and sent on assignments that will emotionally destroy her. Trusts are formed and shattered when she learns truths she never thought possible: who betrayed the guild, and who murdered her parents. The truth presents her with a terrible choice between friendship, duty, and revenge.
You were going great guns until you splatted in paragraph 3.
Let's start with why you chose the oddball construction of "does not come without". A hook is the place for very very plain straigtforward prose. (most agents are reading pretty fast when they read this stuff). "Whisper's offer comes with a price". Then you name the price, only of course you don't. She faces mortal danger ..yea so, big news, my guess is she's done that before if she's trained in thievery, stealth and death.
Then you flail off into blather.
Tighten this up. I'm always interested in fellow alumnae of the Bombaby Sapphire Knife and Gun School for Young Ladies but this one isn't ready for the slush pile yet.