The Archived (The Archived, #1) by Victoria Schwab

In the void between the living and the dead exists a place called The Archive. Here those who have died remain as Histories, curated by Librarians. There they stay asleep but sometimes they wake up, confused and afraid, wandering into The Narrows where they meet Mackenzie Bishop, Keeper. It's her job to return those who have awoken as quickly as possible because the longer a History is awake the more violent they become as they struggle to reach the Outside, our world, where they once belonged. Mackenzie knows that no matter what a History says or does they are not the person they were before. They must be stopped at any cost, even her own life.

Mackenzie's grandfather trained her to take his position when he died. She knows her responsibilities can never be spoken of with anyone. But after losing Da followed by her brother's death for which she holds herself responsible, Mackenzie begins to question the rules of the Archive. Why must they lay in the Archive like books only to be read by the Librarians when their deaths have left gaping holes in her existence. When a History appears that doesn't seem to have any signs of becoming unstable she is faced with a grain of hope that maybe there is a way to bring back her brother and atone for her mistakes. Little does Mackenzie realize that this precise moment has been orchestrated to bring about the end of the Archive from the inside by someone who once was exactly in her shoes. Mackenzie has become the key to destroying the balance and releasing an evil who's only thought is revenge.

A story that hits on the desolation that losing a loved one creates. What would you do if you could bring back someone you loved? Could you be strong enough to let them go again or would you damn them and the world just for one more day? Well written with surprise twists and mystery.