I should first point out that Night is not a novel. It is more of a memoir. This is an important point to keep in mind, because the genre changes the way we read a book.
Night is Eliezer's personal account. The book recounts his years in his hometown in Sighet in Hungary and then his subsequent move to Birkenau and Auschwitz.
During this time, he goes into detail about what he saw and what he experienced. At first he lived in a ghetto in his town. Later he was moved on cattle cars to labor camps. Those who were physically weak were executed. But all were treated worse than animals. He also talks about how he was separated from his mother and sister.
He and they were the walking dead.
The book also recounts pointed scenes that left a mark on Eliezer, such as when he witnessed the hanging a little boy that look a long time because the noose was too big for this boy's neck and the boy too light, or the beautiful violin playing of another young man in the midst of death in a cattle car.
In the end, Eliezer survived, but a part of him died, such as his faith in God.