Scavenger

From the day she lost her sister, Anastasia Scott has had no reason to believe in anything extraordinary. Forced to stay behind with her controlling mother and demeaning boyfriend, Annie has to find some way to cope with her newfound loneliness and the feeling that her sister's death was her own fault. But on the day that a shooter enters her family's memorial hospital, everything changes for Annie. She finds herself betrayed by her mother's assistant, whom she had seen as her only friend. Annie is kidnapped from a home that she never thought she'd miss, only to wake up in the most extraordinary place that she could ever be.
The call themselves END, standing for Eliminate Needless Disorder. They are a secret organization of scientists with the goal of destroying the human race for the start of a better tomorrow. The president, Connor Theiry, is very familiar with Annie, seeing as he had previously tried to murder her mother over eleven years prior to their meeting again. Now, he claims that he needs her, along with the eleven other kids that have been brought into the headquarters.
Annie, who is reluctant to be a part of something as horrible as this, attempts to make her escape, that is, until she is given one piece of crucial information that will fuel her until the very end of their twisted game. If she is to succeed, she will win her sister back.
She is to participate in a twelve-day Hunt for twelve impossible items: truth serum, the list of END's future successes, a soul from the Underworld, the book of Lex, Alice Liddell, a newborn star, the blood of Ramsey, Eve's apple, a lost friend, Selene's fire, Pandora's Box, and the hero's heart. These items will create the disease. These items will be the end for humanity.
Connor promises Annie that it will not be as impossible as it may seem. For one reason: The twelve players have been injected with superpowers.

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Beautiful cover made by @xtruebeautyx