There are hundreds, if not thousands, of Holocaust fiction books in the English language alone. This is not the one to read.
This kind of book is hard to rate. It's based on the true story of Lale Sokolov, a Slovakian Jew who volunteered to go to Auschwitz to save his older brother and, through a combination of true grit and luck, he's able to survive and even fall in love. Who wants to give the story of a Holocaust survivor just two stars? Isn't that a bit heartless?
But it's not subject of the book I'm rating. This book isn't well written. I wasn't surprised to learn that Heather Morris is a screenwriter, because she relies heavily on dialogue here and really struggles with prose (although, to be honest, the dialog leaves a lot to be desired, as well). Scenes change in the matter of a sentence, the dialogue often seems only broken with stage directions. There's no atmospheric build up. There's no sense of tension or urgency or terror. It was all very one-note. The characters, even Lale himself, are flat and poorly developed. The whole book felt very amateurish, and I cannot recommend it.